The CurrentAtomic Model

Atomic Structure• All Material are ultimately made up of

atoms.

• Atoms are the smallest ‘building block’ of matter.

• Each element has a set number of protons eg. Hydrogen has 1 proton, Helium 2 protons and Gold 79 protons

Atomic Structure

• Electrons in shells

• The Nucleons in the Nucleus– Proton– Neutrons

The total number of protons and neutronsin an atom is called its

mass number.

C12

6

The number of protons in an atom is called its

atomic number.

• In a atom…

Number of Electrons = Number of Protons

Electron Configuration

Electron Configuration• The first shell can hold 2 electrons

• The second shell can hold 8 electrons

• The third shell can hold 8 electrons

• The fourth shell can hold 2 electrons

• The electrons always fill up the lowest shell before any other

H

He

Li

Be

F

Ne

Na

Mg

Cl

Ar

K

Ca

• In a atom…

Number of Electrons = Number of Protons

– This means atoms are electrically neutral

– If electrons are added or removed then the atom becomes a charged particle we call an ion

SodiumAtom

ChlorineAtom

PositiveSodium

Ion

NegativeChlorine

Ion