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Metals lose electrons to form positively charged ions(cation).Non-metals gain electrons to form negatively charged ions(anion)

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Non-metals always gain electrons to form negatively charged ions, otherwise known as anions

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Metals always lose electrons to form positively charged ions, otherwise known as cation

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Positively charged-Cation (_______ion
Negatively charged-Anion (_______ide)

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To achieve a stable electronic configuration,the atom can lose or gain electrons to become a Ion.Positively charged Ions are called Cation while negatively charged ions are called anion,some ions who shares cannot be called a cation or anion.

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Carbon can both gain 4 electrons or lose 4 electrons to achieve a stable electronic configuration.

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*The further the electrons from the central nucleus reacts faster.
*When electrons are lost, the elements do not change because the protons are the same.

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1) Across period, elements become less metallic.

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In summary,
1) Down the group, reactivity of elements become greater/more vigorous.
2) Elements in the same group undergo the same type of reaction to give similar products.
(Eg. Alkali metals (Group 1 elements) all move vigorously in water and releases hydrogen gas in water)

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Hydrogen doesn't belong in any group as it can't have a stable electronic configuration unless it either loses an electron and become nothing or gain an electron and become an ion.

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Why does Hydrogen not belong in any group?

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Group 0 elements are also called inert gases as they will not have a chemical reaction due to their stable electronic configuration.

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Group 0 elements are called noble gases as they have achieved a stable electronic configuration as their electron shells are fully filled.

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Why isn't Calcium in Group 0?

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Why does the reactivity of elements down a group become greater although the number of valence electrons are the same?

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The group number determines the number of valence electrons in an element atom.

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Valence electrons cause the chemical reaction and also affects the element's chemical properties.

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Chemical properties; chemical reactions that elements undergo. Eg. Group 1 elements produce hydrogen gas in water.

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1. Rows (Period) of the Periodic Table shows the number of ELECTRONS SHELLS in the atom of an element/Elements in the same period have the same number of ELECTRON SHELLS.
2. Elements in the same group have the same number of ELECTRONS IN THE OUTERMOST ELECTRON SHELL (VALENCE ELECTRONS).

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1. 1st and 4th electron shells can only fill up to 2 electrons
2. 2nd and 3rd electron shells can only fill up to 8 electrons

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Dot-and-cross diagrams show the arrangement of electrons in an electron shells

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Although chlorine only have cl-35 and cl-37 naturally, the average mass is not 36 as there is more cl-35 than cl-37 (75%-25%)

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Can we just randomly make a new element by adding more protons and electrons and neutron signs into atoms of existing elements?

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Isotopes; Atoms of the same elements with the same number of protons and electrons but with different numbers of neutrons, contributing to the different weights of the atoms. Example below:

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Elements in the periodic table is arranged in ascending order of protons from left to right

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The proton number of every element is different.
As every proton is unique .

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1) Only proton & neutron contribute to the mass of an atom.
Mass of atoms = mass (number) of proton + mass (number) of electrons

2) ALL atoms are electrically neutral (overall charge = 0)
Number of proton = number of electron

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Relative mass of.....
Protons- 1
Neutrons- 1
Electrons- 1/1840 (negligible)

Relative charge of......
Protons- +1
Neutrons- 0
Electrons- -1

Number of protons = number of electrons in an atom
Atom is always electrically neutral

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Relative is in comparison of standard numbers hence no units

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# of protons = # of electrons in an atom

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Atom is always electrically neutral

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This only applies to an atom

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The charges always cancel each other out resulting in the atom final charge to be 0, hence, electrically neutral.The neutron does not contribute to the charge at all, therefore number of protons is always equal to the number of electrons

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1) SI unit for charge - Coulombs (C)
2) The charge of an electron is -1 (relative mass)
3) The charge of a proton is +1 (relative mass)
4)The charge of a neutron is 0 (relative mass)

*an atom is always electrically neutral

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SI unit for charge -coulombs(c)[relative charge]

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SI unit for charge -coulombs(c)[relative charge]

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The charge of an electron is -1
The charge of a proton is +1
The charge of a neutron is 0
*An atom is always electrically neutral
Therefore the number of proton shows and electrons must be the same in an  atom

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Only protons and neutrons contribute to the mass of an atom

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We use relative mass as we cannot memorise the mass of protons,neutrons and electrons

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The unit of an atom is called Angstrom

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The sign “Å” represents Angstrom 0.1 nanometer/1x10 to the power of -10 meter
(Nano=10 to the power of -9)

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In comparison to the earth, an atom is the size of a blueberry. When that atom/blueberry is blown up to the size of a football stadium, The Central nucleus of the atom is the size of a marble.

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Electrons are free flowing in the electron cloud model

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Electron Cloud Model

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1803 JOHN DALTON
-set the foundation for atomic theory
-He claim that atoms cannot be broken down into anything simpler.
1897 J.J THOMPSON
-prove John Dalton wrong about one of his claim by finding electrons
-created the "plum pudding model"
1911 ERNEST RUTHERFORD
-prove that J.J Thompson atomic model is wrong by finding out that atoms has a central nucleus
Niels Bohr
-claim that electrons orbits around the central nucleus
John Chadwick
-found neutrons and prove that  Ernest Rutherford claim is wrong and that central nucleus is made up of both protons and neutrons.
Erwin Schrodinger
-prove that Niels Bohr is wrong and that electrons surround the central nucleus like a cloud

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There is no gap between the central nucleus and the electron shell as Erwin Schrodinger prove that Niels Bohr is wrong and created the new theory about electrons completely surrounding the central nucleus.

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John Chadwick discovered that the central nucleus is not just made up of protons but also neutrons,with supporting evidence (the mass of the central nucleus is 2 times the mass of protons) proving that Ernest Rutherford claim about the central nucleus is only made up of protons wrong.

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J.J Thompson believed that the sub atomic particles in the plum pudding model are evenly distributed.

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Kinetic particle theory studies the properties of the different states of matter.Atomic theory is going in deeper into each atoms that form the different states of matter.

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How small is an atom really?

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Erwin Schrödinger did not agree with Bohr’s model, saying it does not define the exact path of the electron. He also disagreed that the electrons do not just move around in the orbit. Schrödinger discovered the electron cloud model which was the gap between the central nucleus and the electron shell.

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Where the cloud is most dense ,the chance of finding the electron is greatest ,and conversely,the electron is less likely to be in a less dense area of the cloud.

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Bohr’s model still does not explain everything (no mention of neutrons, the gap between the central nucleus and the electron shell,etc)

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What is the GAP between the protons and electron shell ?

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Niels Bohr believe that electrons occupy particular orbits or shells around the nucleus of an atom. Bohr’s model below:

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Rutherford’s model (central nucleus)

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JJ Thomson discovered that there are sub-atomic particles called electrons
PLANT PUDDING model:

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One of Dalton’s conclusions are wrong in which atoms actually can be broken down into simpler substances called sub-atomic particles or electrons specifically which JJ Thompson discovered.

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Conclusions from John Dalton’s experiments on atomic theory

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Conclusions from John Dalton’s experiments on atomic theory

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All matter is made of atoms
Atoms cannot be broken down into anything simpler
All the atoms of a particular element are identical to each other and different from the atoms of other elements
Atoms are rearranged in a chemical reaction
Compounds are formed when two or more different kinds of atoms join together