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8U1 - 5(A) describe the structure of , including the , electrical charges, and locations, of and in the nucleus and in the cloud; is anything that takes up space. All Matter is composed of tiny called ATOMS.

Surprisingly, in the entire there are only 118 different kinds of atoms. Here on , there are approximately 70 different kinds of common atoms. We call them ELEMENTS. Elements are only made up of one kind of .

The smallest possible element would be one and one electron. This is the element .

The next possible element is 2 protons and 2 electrons. This is the element . Next is Litium, with 3 electrons and 3 protons. The progression of the elements is shown below.

Atom the smallest into which an element can be divided and still have the properties of that element; consists of protons, neutrons, and electrons

atom Smallest particle of an element.

electron A tiny, negatively that moves around the nucleus of an atom

Electrons The electrons are moving VERY fast around the nucleus

Proton positively charged particle located in the nucleus of an atom Protons determine the identity of the atom.

A that has no charge and that is found in the nucleus of an atom

nucleus of The protons and neutrons are held atom together in the positively charged nucleus of the atom

If the atoms are packed closely together, we have a

SOLID

IF the atoms are loosely connected to each other, we have a

LIQUID

If the atoms are not connected at all, we have a

GAS

Each atom consists of 3 parts: Protons and neutrons in the nucleus, with electrons orbiting in orbitals.

atom the basic building block of matter

Electron each electron has 1 unit of negative charge

• proton Each proton has 1 unit of positive charge

neutron A particle without an electrical charge within the

Isotope An atom with the same number of protons and a different number of neutrons from other atoms of the same element.

Nucleus The center of an atom that contains the (Atom) protons and neutrons

Neutral Atoms are neutral – the number of positive protons is exactly the same as the number of negative electrons, resulting in a net charge of zero.

Molecule Groups of two or more atoms held together by chemical bonds

How elements generally prefer to form bonds so as to attain eight electrons in their outer shell

Valence An electron in an outer shell of an atom Electrons that can participate in forming chemical bonds with other atoms

Argon electrons = ?

8

Potassium Valence electrons = ?

1

Nitrogen Valence electrons = ?

5

8U1 - 5(B) identify that protons determine an element's identity and valence electrons determine its chemical properties, including reactivity;

Valence electrons determine how an element will react with other substances.

Elements in the same Group / Family have the same number of valence electrons. This is why elements in the same Group / Family have similar properties and reactivites.