Atomic Structure

Nucleus

Outer electron shell

Inner electron shell

Proton

Neutron

Sub Atomic Particles

• 1. PROTONS- positive electrical charge, found in the NUCLEUS, or center of an atom.

• 2. NEUTRONS- neutral (no electrical charge), also found in the NUCLEUS.

• 3. ELECTRONS- negative electrical charge, found moving around the nucleus in the ELECTRON CLOUD

Friendly electrons

• Electrons like to travel in pairs, when they can find another electron to travel with.

• Different layers within the electron cloud are called ENERGY LEVELS or SHELLS

Friendly electrons

• Electrons like to travel in pairs, when they can find another electron to travel with.

• Different layers within the electron cloud are called ENERGY LEVELS or SHELLS

Atomic Number?

How many bonds will this form?

How many Protons?

Electron shells

• The first shell can hold 2 electrons.

• The second shell can hold 8 electrons.

• The third shell also holds 8 electrons.

Electrons exist in shells around the nucleus.

H 1 p+ (1 e-)

He 2 p+ (2 e-)

Li 3 p+ (3 e-)

C 6 p+ (6 e-)

N 7 p+ (7 e-)

O 8 p+ (8 e-)

How to find atomic structure

• ATOMIC NUMBER = protons in the nucleus

• Each different atomic number is a new ELEMENT, or pure substance that cannot be broken down

How to find atomic structure

• ATOMIC MASS = protons PLUS neutrons in the nucleus

• Atomic Mass- Atomic Number = neutrons

Periodic TableAlkali Metals

Halogens

Noble Gases

Information in the Table

Ag107.87

Silver47 Atomic number

Name of the element

Elemental Symbol

Atomic mass (weight)

• 109 elements are currently known:

• (Don’t need to know this!)– 87 are metals– 26 are radioactive– 16 are man made (all radioactive)– 11 occur as gases– 2 occur as liquids

Navigating the Periodic Table• The rows are the “periods”

– Each period starts a new shell of electrons– The periods are numbered starting with 1 at the

top • The columns are the “groups”

– Each group has similar chemical properties– The groups are numbered starting with 1 at the

left– Elements with similar properties have the

same number of electrons in the outermost shell

Chemical Families

• Chemical Families– Group 1 are called alkali metals because the react

with water to from an alkaline solution, very soft metals.

– Group 7 are the halogens• These need only one electron to fill their outer shell

• They are very reactive.( disinfectants, bleach, headlights)

– Group 0 are the noble gases as they have completely filled outer shells

• They are almost non reactive.