8U1 - 5(A) describe the structure of atoms, including the masses, electrical

charges, and locations, of protons and neutrons in the nucleus and electrons in

the electron cloud;

Matter is anything that takes up space. All Matter is composed of tiny particles called ATOMS.

Surprisingly, in the entire universe there are only 118 different kinds of atoms. Here on earth,

there are approximately 70 different kinds of common atoms. We call them ELEMENTS.

Elements are only made up of one kind of atom.

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

hydrogen.

The next possible element is 2 protons and 2 electrons. This is the element Helium. Next is

Litium, with 3 electrons and 3 protons. The progression of the elements is shown below.

Atom the smallest particle 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 charged particle 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.

neutron A subatomic particle that has no charge

and that is found in the nucleus of an

atom

nucleus of

atom

The protons and neutrons are held

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 atomic nucleus

Isotope An atom with the same number of

protons and a different number of

neutrons from other atoms of the same

element.

Nucleus

(Atom)

The center of an atom that contains the

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

octet rule How elements generally prefer to form

bonds so as to attain eight electrons in

their outer shell

Valence

Electrons

An electron in an outer shell of an atom

that can participate in forming chemical

bonds with other atoms

Argon Valence 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.