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He arranged all the elements known at the time into a table in order of relative atomic mass. When he did this, he found a pattern among the early elements. The pattern showed that each element was similar to the element eight places ahead of it.

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The Bohr model shows the atom as a small, positively charged nucleus surrounded by orbiting electrons. Bohr was the first to discover that electrons travel in separate orbits around the nucleus and that the number of electrons in the outer orbit determines the properties of an element.

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Ernest Rutherford found that the atom is mostly empty space, with nearly all of its mass concentrated in a tiny central nucleus. The nucleus is positively charged and surrounded at a great distance by the negatively charged electrons. Rutherford discovered this by bombarding gold foil with beryllium.

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Structure Matters: Twenty-One Teaching Strategies to Promote Student Engagement and Cultivate Classroom Equity

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Structure Matters: Twenty-One Teaching Strategies to Promote Student Engagement and Cultivate Classroom Equity

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While this is orientated towards a biology classroom I believe that most of it also applies to a chemistry classroom also as the sciences are closely linked

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If the address matches an existing account you will receive an email with instructions to retrieve your username

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Éadaoin Stafford - 20253745 - SE4034 Reflection

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~2 billion atoms fit in a full stop.
~ A strand of human hair is about 1 million atoms wide

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About 440 BC Democritus, a Greek philosopher came up with the word atom. In Greek 'a' means 'not' and tomos' means 'cut' so together these words mean 'cannot be cut' or 'indivisible'.

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My chosen learning outcome LO 3  links with LO 4 and LO 5. These three learning outcomes link together to form an unit of learning. In my UOL I will be focusing on all three learning outcomes as they flow nicely into each other and have strong links for understanding.
See Below

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Science Collaborative Planning Document 

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Science Collaborative Planning Document docx

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The Conical Flask website has simple notes which are easy for students to comprehend and understand.

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Newlands' Law of Octaves is an early attempt to classify elements based on periodic properties. It set the stage for later, more complete methods like Mendeleev's and the Modern Periodic Table.

History

Newlands' Law of Octaves was proposed in 1865 by John Newlands, a British chemist. He arranged the known elements in increasing order of atomic weight, and suggested that after every eight elements shared properties were noticed. This he compared to a musical term called the " octave " for 8 notes.

His work was an improvement over previous work such as that of Dobereiner, who made a smaller attempt called Dobereiner Triads.

However, Newlands Law of Octaves was not taken seriously by the scientific community at that time.

Features of Newlands Octaves

Here are some major features of Newlands' Law of Octaves

Newlands Octaves arranged the known 62 elements then into roughly 8 groups of 8 each.

The elements were in increasing order of atomic weight.

Every element shared properties with the 8th element after it.

Sometimes two elements were made to occupy one place, to reflect their properties.

This was one of the largest early attempts to arrange all known elements in a specific order.

Limitations of Newlands Law of Octaves

Newlands' Octaves had some limitations which we discuss below.

While the groups had similar features, there were also some dissimilar elements in same group. For example, metals like platinum, cobalt and nickel, were in the same group as halogens like chlorine and bromine.

In some slots, two elements had to share the same place. For example, cobalt and nickel, or barium and vanadium. There was no clear explanation for this.

The law strictly worked well only upto Calcium, for heavier elements the relationship began to break down.

There were no spaces left for future elements that were discovered. This meant that future elements disrupted the pattern.

FAQs

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Newlands Law of Octaves - Features, Limitations | ProtonsTalk

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Newlands' Law of Octaves is an early attempt to classify elements based on periodic properties. It set the stage for later, more complete methods like Mendeleev's and the Modern Periodic Table. Newlands' Law of Octaves was proposed in 1865 by John Newlands, a British chemist.

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https://www.electrical4u.com/concept-of-atom/

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An atom is defined as the smallest particle of a substance that can exist by itself or be combined with other atoms to form a molecule.

In the year 1808, famous English chemist, physicist, and meteorologist John Dalton published his theory of the atom. At that time, many unexplained chemical phenomena got quickly unlocked by Dalton's theory. Hence, the theory became a theoretical foundation of chemistry. The postulates of Dalton's atomic theory were as follows.

All matter is made up of small indivisible and indestructible particles called atoms.

All atoms of the same element have identical properties but differ from atoms of other elements.

Atoms of different elements combine together to form a compound.

A chemical reaction is nothing but a rearrangement of these atoms.

Atoms cannot be created or destroyed by any means.

Dalton's theory had certain drawbacks like; today we know that atoms can be destroyed. Also, some atoms of the same elements vary in their mass(isotopes). The theory also fails to explain the existence of allotropes.

But in mordern era concept of atom is based on the combining the merits of Rutherford's atomic model and Bohr's atomic model. All substances are made up of atoms. All atoms consist of,

Nucleus of Atom

Nucleus is located at the center of atom. The diameter of nucleus is about 1/10000 of diameter of whole atom. Almost whole mass of atom is concentrated in its nucleus. Nucleus itself consists of two kinds of particles,

Proton

Protons are positively charged particles. Charge on each proton is 1.6 × 10⁻¹⁹ Coulomb. The number of protons in nucleus of an atom represents the atomic number of atom.

Neutron

Neutrons do not have any electrical charge. Means, neutrons are electrically neutral particles. The mass of each neutron is equal to mass of the proton.
The nucleus is positively charged due to the presence of positively charged protons. In any material, the weight of the atom and radioactive properties are associated with the nucleus.

Electrons

An electron is a negatively charged particle present in the atoms. Charge on each electron is - 1.6 × 10 - 19 Coulomb. These electrons surround the nucleus. Some facts about electrons in an atom are listed and explained below,

If an atom is having the same number of protons and electrons, the atom is electrically neutral as the negative charge of electrons neutralizes the positive charge of protons.

The electrons revolve around the nucleus in shells (also called orbits).

A force of attraction is excreted on negatively charged electrons by positively charged nucleus. This force of attraction works as centripetal force required for electrons revolution around the nucleus.

The electrons which are near to nucleus are tightly bound with the nucleus and it is more difficult to pull out (remove) these electrons from the atom than those which are far away from the nucleus.

The structure of aluminum atoms is shown in figure below-

A definite amount of energy is required to remove the electron from its orbit. The energy required to remove the electron from the first orbit is much more as compared to the energy required to remove the electron from the outer orbit. This is due to the force of attraction excreted by nucleus on electrons in the first orbit is much more as compared to the force of attraction excreted on electrons of outer orbit. Similarly, the energy required to remove the electron from the second orbit will be less as compared to the first orbit and greater than the third orbit. Hence, we can say that the electrons in the orbit are associated with a definite amount of energy. Thus the orbits or shells are also referred as energy levels.

The energy levels are denoted by the letters K, L, M, N, etc. Where, K is the nearest orbit to the nucleus and having lowest energy level. Conversely, the outermost orbit is having highest energy level.

The maximum number of electrons in any energy level is given by, '2n²', where, n is an integer and represents the "principal quantum number". For different energy levels the value of 'n' and maximum number of electrons as given in table below

The above formula (2n²) used for determining the maximum number of electrons in any shell, has some limitations. The Number of electrons in outermost shell (highest energy level) cannot exceed beyond 8. For example let's consider the atom of calcium, it is having 20 electrons orbiting around its nucleus. As per formula of above rule i.e. 2n², the electrons distribution will be as 2 electrons in K level, 8 electrons in L level and there will be balance 10 electrons. But the electrons in outer most energy level cannot exceed 8. Hence, there will be 8 electrons in M level and balance 2 electrons will go to next energy level i.e. 2 electrons will go the N level. The electron configuration of Calcium atom is shown in figure below-

The electrons in the outermost energy level are called "valence electrons". The maximum possible number of "valence electrons" is 8. If the number of electrons in outermost orbit is 8, the atom becomes stable. The material whose atoms naturally having 8 electrons in their outermost shell (orbit), does not react with other material. Inert gases such as Helium, Neon, Argon, krypton etc. are having completely filled outer most shells and hence do not react with other materials.

The "valence electrons" of an atom are loosely bound with the nucleus and can be freed / removed by different method i.e. by heating, by applying electric voltage etc.

The "valence electrons" form the bonds to hold the atoms of material together. Most of the properties of materials are determined by these bonds in materials.

The each main shell (energy level) is subdivided into sub shells. These sub shell are called orbitals. These sub shell /orbitals are designated by s, p, d, f etc. with corresponding quantum number, l = 0, 1, 2, 3, 4,....(n-1) etc. The number of sub shells in any main shell is equal to principal quantum number 'n'. The electron capacity of any main shell can be determined by adding the electron capacity of sub shells. The maximum electron capacity of sub shells is governed with the formula of 2(2l +1 ). The capacities of sub shells are given in table below-

First shell i.e. K shell will have principal quantum number 1 and one s orbital and hence the s orbital is denoted as 1s.

The second shell i.e. L shell will have principal quantum number 2 and will have one s and one p orbital and they are denoted as 2s and 2p respectively.

The third shell i.e. M shell will have principal quantum number 3 and will have one s, one p, and one d orbital and they are denoted as 3s, 3p and 3d respectively and so on.

Here we have another thing to remember that s orbital has one suborbital and every sub-orbital can contain maximum two electrons. The p orbital has 3 suborbital and d orbital has 5 suborbital.

The lower energy suborbital are first filled up and then next higher orbital is filled. There would not be any chance of filling up any higher orbital or suborbital before filling is completed in its lower orbital.

If we go through the examples below it will be clear to us.

Atomic Structure of Aluminum having 13 Electrons

Atomic Structure of Copper having 29 Electrons

Here it can be noticed that 3d orbital is in higher energy level than 4s similarly 4d orbital is in higher energy level than 5s similarly. Here it can be noticed that 3d orbital is in higher energy level than 4s
Atomic Structure of Silver having 47 Electrons

Modern Atomic Theory

The modern atomic theory is just little more evolved than the Dalton's Theory. Modern atomic theory is also called as quantum theory. The concept of wave particle duality comes into picture here. It says that the electrons which are considered to be particles can sometimes behave like waves. So an atom has a nucleus which is surrounded by probability clouds. These clouds are the most probably locations of electrons. The size and shape of these clouds can be calculated by using the equations of the waves.

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An atom is defined as the smallest particle of a substance that can exist by itself or be combined with other atoms to form a molecule. In the year 1808, famous English chemist, physicist, and meteorologist John Dalton published his theory of the atom. At that time, many unexplained chemical…

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CW 3 Lesson Plan

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Atoms with the same number of protons but different number of neutrons.

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Empedocles devised the theory that all substances are made of four pure, indestructible elements: air, fire, water, and earth. It is admirable that Empedocles tried to simplify our complex world into basic elements. This theory was created around 450 BC

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Chemical Bonding - Atomic Structure and Bonding

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Chemical Bonding - Atomic Structure and Bonding

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This shows a much greater understanding of chemical bonding than is necessary. But has some good points which will allow for a good explanation. it also shows Neils Bohr's Atomic Structure.

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To understand bond formation, it is necessary to know the general features of the electronic structure of atoms-that is, the arrangement of electrons around the central nucleus. For background information about this subject and further details, see atom.

Atomic structure

The modern version of atomic structure begins with Ernest Rutherford's recognition that an atom consists of a single, central, massive, positively charged nucleus surrounded by electrons. The number of protons in the nucleus is the atomic number, Z, of the element. (For hydrogen Z = 1, and for carbon Z = 6.) A proton is positively charged, and an electron carries an equal but opposite negative charge. For an atom to be electrically neutral, it must contain the same number of extranuclear electrons as there are protons in the nucleus. Hence, the number of electrons in a neutral atom of atomic number Z is also Z. A hydrogen atom consequently has one electron, and a carbon atom has six electrons.

The first attempt to introduce quantum theory to account for the structure of atoms was made by the Danish physicist Niels Bohr in 1913. He asserted that the electron in a hydrogen atom occupies one of an array of discrete (but infinite in number) orbits, each orbit being progressively farther from the nucleus and labeled with an integer n = 1, 2,.... This integer is an example of a quantum number, which in general is an integer (in some cases, a half-integer) that labels the state of a system and which, through an appropriate formula, determines the values of certain physical properties of the system. By matching the centrifugal effect of the electron's motion in its orbit to the electrostatic attraction of the nucleus for the electron, Bohr was able to find a relation between the energy of the electron and the quantum number of its orbit. The result he obtained was in almost perfect agreement with the observed values of the energy levels of a hydrogen atom that had previously been obtained by spectroscopic methods.

Bohr's triumph was the first apparently successful incorporation of quantum theoretical ideas into the description of a mechanical system. The numerical success of the model has turned out to be coincidental, however, and Bohr's model is now regarded as no more than a historically important step in the evolution of quantum mechanics. The cracks in its validity were noted quite soon after its introduction. Thus, it was remarked that Bohr had not really derived the existence of discrete orbits from more fundamental principles but had merely imposed them on the model. Furthermore, all attempts to extend his theory to atoms that consisted of more than one electron ( helium, with two electrons, for instance) utterly failed. Although the model was augmented by more elaborate specifications of the orbits (most notably, first, by allowing for elliptical orbits and introducing a second quantum number to specify the elongation of the ellipse and, second, by allowing for the effects of relativity), the failure to generalize to many-electron atoms remained a fatal flaw.

The quantum mechanical model

Current understanding of atomic structure had to await the introduction of quantum mechanics by the scientists Werner Heisenberg of Germany and Erwin Schrödinger of Austria in the mid-1920s. Indeed, the structure of the hydrogen atom that is still employed today was developed by Schrödinger in the four papers with which he introduced his version of quantum mechanics-wave mechanics-to the world. The quantum mechanical model of the hydrogen atom has the same numerical agreement with experiment that proved so coincidental with the Bohr model, but it is more fundamentally founded (i.e., the discreteness of the allowed energy states emerges from more general aspects and is not imposed), and the model can be extended (albeit with difficulty) to many-electron atoms. Moreover, unlike Bohr's theory, it is consistent with the fundamental principles of quantum mechanics-specifically the wave character of the electron and the requirements of the uncertainty principle, which states that the position and momentum (mass times velocity) of a particle cannot be specified simultaneously.

The location of the electron

In the quantum mechanical model of the hydrogen atom, the location of the electron is expressed in terms of a probability distribution, so one speaks of the probability that an electron will be found at a particular location near a nucleus. The probability distribution, in turn, is determined by a mathematical function known as a wave function, denoted ψ. Wave functions for the distribution of particles are a general feature of quantum mechanics, and for electrons in atoms they are known as atomic orbitals. The name orbital is intended to express a distribution that is less precise than the explicit orbits of the Bohr model. The probability of finding an electron at a specified location is proportional to the square of the amplitude of the wave function at that point. Hence, the sign (positive or negative) of the orbital is not relevant to the location of the electron, because taking the square of ψ eliminates any negative sign it may have. However, as explained below in Molecular orbital theory, the sign is of crucial importance in the discussion of bonding between atoms and so cannot be ignored.

Three quantum numbers are needed to specify each orbital in an atom, the most important of these being the principal quantum number, n, the same quantum number that Bohr introduced. The principal quantum number specifies the energy of the electron in the orbital, and, as n increases from its lowest value 1 through its allowed values 2, 3,..., the energies of the corresponding orbitals increase. The ground state, or lowest energy state of the hydrogen atom, is the state in which it is normally found and has n = 1, it consists of a single electron in the orbital closest to the nucleus. As n increases, so does the average distance of the electron from the nucleus, and, as n approaches infinity, the average distance also approaches infinity. The energy required to elevate the electron from the orbital with n = 1 to the orbital with n = ∞ is called the ionization energy of the hydrogen atom; this is the energy required to remove the electron completely from the atom.

The quantum number n labels the shell of the atom. Each shell consists of n ² individual orbitals with the same principal quantum number and hence (in the hydrogen atom) the same energy. Broadly speaking, each shell consists of orbitals that lie at approximately the same distance from the nucleus. The shells resemble the layers of an onion, with successive shells surrounding the inner shells.

The next quantum number needed to specify an orbital is denoted l and called the orbital angular momentum quantum number. This quantum number has no role in determining the energy in a hydrogen atom. It represents the magnitude of the orbital angular momentum of the electron around the nucleus. In classical terms, as l increases, the rate at which the electron circulates around the nucleus increases. The values of l in a shell of principal quantum number n are limited to the n values 0, 1, 2,..., n − 1, and the value of l of an orbital in a given shell determines the subshell to which that orbital belongs. It follows from the allowed values of l that there are n subshells in a shell of principal quantum number n. As will be explained, there are 2 l + 1 orbitals in a given subshell.

Although subshells are uniquely specified by the values of n and l, it is conventional to label them in a slightly different manner. A subshell with l = 0 is called an s subshell, one with l = 1 is called a p subshell, and one with l = 2 is called a d subshell. Other subshells are encountered, but these three are the only ones that need to be considered here. The three subshells of the shell with n = 3, for example, are called the 3 s, 3 p, and 3 d subshells.

As noted above, a subshell with quantum number l consists of 2 l + 1 individual orbitals. Thus, an s subshell ( l = 0) consists of a single orbital, which is called an ; a p subshell ( l = 1) consists of three orbitals, called ; and a ( l = 2) consists of five orbitals, called d orbitals. The individual orbitals are labeled with the magnetic quantum number, m, which can take the 2 l + 1 values l, l − 1,..., − l. The orbital occupied in the lowest energy state of the hydrogen atom is called a 1 s orbital, signifying that it belongs to (and is in fact the only member of) the shell with n = 1 and subshell with l = 0.

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chemical bonding - Atomic structure and bonding

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To understand bond formation, it is necessary to know the general features of the electronic structure of atoms-that is, the arrangement of electrons around the central nucleus. For background information about this subject and further details, see atom.

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Is a charged atom or group of atoms.

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Describe the physical and chemical characteristics of a substance.

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Mendeleev found that, when all the known chemical elements were arranged in order of increasing atomic weight, the resulting table displayed a recurring pattern, or periodicity, of properties within groups of elements.

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John Newlands initally arranged the known elements into octaves. He noted that every eight element had similar properties and characteristics

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Is the number of protons in a nucleus.

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Is how electrons are arranged in the shells/orbits.

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Are subatomic particles that have a negative charge, -1.

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Are subatomic particles that have no charge.

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Are subatomic particles that have a positive charge, +1.

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Is the center of the atom. This contains protons and neutrons.

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Small particles that make up an atom

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Are simple substances that consist of only one type of atom

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Two or more atoms chemically combined

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Students should be able to describe and model the structure of the atom in terms of the nucleus, protons, neutrons and electrons; comparing mass and charge of protons, neutrons and electrons.

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CW 2, CW 4, CW 5, NOS 1,N0S 4, PW 3

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Action Verbs - Definitions and Related Learning Outcomes

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The smallest particle that makes up a substance

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When two or more elements combine chemically, a compound is formed

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Is the total number of protons and neutrons in a nuclues.