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Make a copy and complete the tasks to review your mastery of the parts of an Atom! Turn in to Google Classroom when you are done!

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Atomic Structure Interactive Digital Worksheet

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Complete this on KAMI (or on paper, if you prefer)

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Complete this on KAMI (or on paper, if you prefer)

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Complete this on KAMI (or on paper, if you prefer)

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The History of Atomic Chemistry: Crash Course Chemistry #37

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Answer questions via Kami (or on paper if you prefer) https://www.youtube.com/watch?v=1DlnH1SW4wQ&t=4s&pp=ygUOYmlsbCBueWUgYXRvbXM%3D

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The number of neutrons in a nucleus affects the mass of the atom but not its chemical properties. Thus, a nucleus with six protons and six neutrons will have the same chemical properties as a nucleus with six protons and eight neutrons, although the two masses will be different. Nuclei with the same number of protons but different numbers of neutrons are said to be isotopes of each other. All chemical elements have many isotopes.

It is usual to characterize different isotopes by giving the sum of the number of protons and neutrons in the nucleus-a quantity called the atomic mass number. In the above example, the first atom would be called carbon-12 or ¹²C (because it has six protons and six neutrons), while the second would be carbon-14 or ¹⁴ C.

The mass of atoms is measured in terms of the atomic mass unit, which is defined to be ¹/ ₁₂ of the mass of an atom of carbon-12, or 1.660538921 × 10 −24 gram. The mass of an atom consists of the mass of the nucleus plus that of the electrons, so the atomic mass unit is not exactly the same as the mass of the proton or neutron.

Charge, mass, and spin

See how physicist Robert Millikan devised a method for measuring the electric charge of single electrons

Encyclopædia Britannica, Inc. See all videos for this article

Scientists have known since the late 19th century that the electron has a negative electric charge. The value of this charge was first measured by the American physicist Robert Millikan between 1909 and 1910. In Millikan's oil-drop experiment, he suspended tiny oil drops in a chamber containing an oil mist. By measuring the rate of fall of the oil drops, he was able to determine their weight. Oil drops that had an electric charge (acquired, for example, by friction when moving through the air) could then be slowed down or stopped by applying an electric force. By comparing applied electric force with changes in motion, Millikan was able to determine the electric charge on each drop. After he had measured many drops, he found that the charges on all of them were simple multiples of a single number. This basic unit of charge was the charge on the electron, and the different charges on the oil drops corresponded to those having 2, 3, 4,... extra electrons on them. The charge on the electron is now accepted to be 1.602176565 × 10 −19 coulomb. For this work Millikan was awarded the Nobel Prize for Physics in 1923.

The charge on the proton is equal in magnitude to that on the electron but opposite in sign-that is, the proton has a positive charge. Because opposite electric charges attract each other, there is an attractive force between electrons and protons. This force is what keeps electrons in orbit around the nucleus, something like the way that gravity keeps Earth in orbit around the Sun.

The electron has a mass of about 9.109382911 × 10 −28 gram. The mass of a proton or neutron is about 1,836 times larger. This explains why the mass of an atom is primarily determined by the mass of the protons and neutrons in the nucleus.

The electron has other intrinsic properties. One of these is called spin. The electron can be pictured as being something like Earth, spinning around an axis of rotation. In fact, most elementary particles have this property. Unlike Earth, however, they exist in the subatomic world and are governed by the laws of quantum mechanics. Therefore, these particles cannot spin in any arbitrary way, but only at certain specific rates. These rates can be ¹/ ³/ ¹/ ₂ . ₂ , 2,... times a basic unit of rotation. Like protons and neutrons, electrons have spin ₂ , 1,

Particles with half-integer spin are called fermions, for the Italian American physicist Enrico Fermi, who investigated their properties in the first half of the 20th century. Fermions have one important property that will help explain both the way that electrons are arranged in their orbits and the way that protons and neutrons are arranged inside the nucleus. They are subject to the Pauli exclusion principle (named for the Austrian physicist Wolfgang Pauli), which states that no two fermions can occupy the same state-for example, the two electrons in a helium atom must have different spin directions if they occupy the same orbit.

Because a spinning electron can be thought of as a moving electric charge, electrons can be thought of as tiny electromagnets. This means that, like any other magnet, an electron will respond to the presence of a magnetic field by twisting. (Think of a compass needle pointing north under the influence of Earth's magnetic field.) This fact is usually expressed by saying that electrons have a magnetic moment. In physics, magnetic moment relates the strength of a magnetic field to the torque experienced by a magnetic object. Because of their intrinsic spin, electrons have a magnetic moment given by −9.28 × 10 −24 joule per tesla.

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atom - atom - Atomic mass and isotopes: The number of neutrons in a nucleus affects the mass of the atom but not its chemical properties. Thus, a nucleus with six protons and six neutrons will have the same chemical properties as a nucleus with six protons and eight neutrons, although the two masses will be different.

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Khan Academy: Atomic Number, Atomic Mass, and Isotopes

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Khan Academy: Atomic Number, Atomic Mass, and Isotopes

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Read through the tutorial and then do the practice!

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In this simulation, students first learn how the average atomic mass is determined through a tutorial based on the isotope abundance for Carbon. Students will then interact within a workspace where they will select the number of isotopes, the mass of each isotope as well as their abundancies in order to successfully build a mystery element. Finally they will use their choices to calculate the average atomic mass of the mystery element.

This simulation was developed through generous funding provided by The Camille & Henry Dreyfus Foundation
See accompanying lesson plan

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Classroom Resources | Isotopes & Calculating Average Atomic Mass | AACT

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In this simulation, students first learn how the average atomic mass is determined through a tutorial based on the isotope abundance for Carbon. Students will then interact within a workspace where they will select the number of isotopes, the mass of each isotope as well as their abundancies in order to successfully build a mystery element.

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ACS Protons, Neutrons, and Electrons Simulation Pratice 

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ACS Protons, Neutrons, and Electrons Simulation Pratice 

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Explore the simulations on this page, refresh them and try again as needed!

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Simulations & Videos for Lesson 4.1: Protons, Neutrons, and Electrons - American Chemical Society

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American Chemical Society: Chemistry for Life.

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150 years ago, the periodic table began with one chemist’s vision

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150 years ago, Russian chemist Dmitrii Mendeleev created the periodic table of the elements, revolutionizing chemistry.

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What is the periodic table?

What do periodic table groups have in common?

Where does the periodic table come from?

Why does the periodic table split?

periodic table, in chemistry, the organized array of all the chemical elements in order of increasing atomic number-i.e., the total number of protons in the atomic nucleus. When the chemical elements are thus arranged, there is a recurring pattern called the "periodic law" in their properties, in which elements in the same column (group) have similar properties. The initial discovery, which was made by Dmitry I. Mendeleyev in the mid-19th century, has been of inestimable value in the development of chemistry.

It was not actually recognized until the second decade of the 20th century that the order of elements in the periodic system is that of their atomic numbers, the integers of which are equal to the positive electrical charges of the atomic nuclei expressed in electronic units. In subsequent years great progress was made in explaining the periodic law in terms of the electronic structure of atoms and molecules. This clarification has increased the value of the law, which is used as much today as it was at the beginning of the 20th century, when it expressed the only known relationship among the elements.

History of the periodic law

The early years of the 19th century witnessed a rapid development in analytical chemistry-the art of distinguishing different chemical substances-and the consequent building up of a vast body of knowledge of the chemical and physical properties of both elements and compounds. This rapid expansion of chemical knowledge soon necessitated classification, for on the classification of chemical knowledge are based not only the systematized literature of chemistry but also the laboratory arts by which chemistry is passed on as a living science from one generation of chemists to another. Relationships were discerned more readily among the compounds than among the elements; it thus occurred that the classification of elements lagged many years behind that of compounds. In fact, no general agreement had been reached among chemists as to the classification of elements for nearly half a century after the systems of classification of compounds had become established in general use.

Periodic Table of the Elements

J.W. Döbereiner in 1817 showed that the combining weight, meaning atomic weight, of strontium lies midway between those of calcium and barium, and some years later he showed that other such " triads" exist (chlorine, bromine, and iodine [halogens] and lithium, sodium, and potassium [alkali metals]). J.-B.-A. Dumas, L. Gmelin, E. Lenssen, Max von Pettenkofer, and J.P. Cooke expanded Döbereiner's suggestions between 1827 and 1858 by showing that similar relationships extended further than the triads of elements, fluorine being added to the halogens and magnesium to the alkaline-earth metals, while oxygen, sulfur, selenium, and tellurium were classed as one family and nitrogen, phosphorus, arsenic, antimony, and bismuth as another family of elements.

Attempts were later made to show that the atomic weights of the elements could be expressed by an arithmetic function, and in 1862 A.-E.-B. de Chancourtois proposed a classification of the elements based on the new values of atomic weights given by Stanislao Cannizzaro's system of 1858. De Chancourtois plotted the atomic weights on the surface of a cylinder with a circumference of 16 units, corresponding to the approximate atomic weight of oxygen. The resulting helical curve brought closely related elements onto corresponding points above or below one another on the cylinder, and he suggested in consequence that "the properties of the elements are the properties of numbers," a remarkable prediction in the light of modern knowledge.

Classification of the elements

In 1864, J.A.R. Newlands proposed classifying the elements in the order of increasing atomic weights, the elements being assigned ordinal numbers from unity upward and divided into seven groups having properties closely related to the first seven of the elements then known: hydrogen, lithium, beryllium, boron, carbon, nitrogen, and oxygen. This relationship was termed the law of octaves, by analogy with the seven intervals of the musical scale.

Then in 1869, as a result of an extensive correlation of the properties and the atomic weights of the elements, with special attention to valency (that is, the number of single bonds the element can form), Mendeleyev proposed the periodic law, by which "the elements arranged according to the magnitude of atomic weights show a periodic change of properties." Lothar Meyer had independently reached a similar conclusion, published after the appearance of Mendeleyev's paper.

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Periodic table | Definition, Elements, Groups, Charges, Trends, & Facts

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Periodic table, in chemistry, the organized array of all the chemical elements in order of increasing atomic number. When the elements are thus arranged, there is a recurring pattern called the 'periodic law' in their properties, in which elements in the same column (group) have similar properties.

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In this interactive activity from ChemThink, learn about atomic structure. Follow the tutorial to understand how individual atoms-the basis of all matter-are composed of subatomic particles such as electrons, protons, and neutrons. Investigate the three types of particles, their properties (such as mass and charge), and relative locations.