Atomic Structure

Atoms And the Periodic Table

Atomic Structure Inner electron shell Proton Nucleus

Neutron

Outer electron shell

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

N

e-)

6 p+

7 p+

(6

(7 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

Alkali Metals

Periodic Table

Halogens

Noble Gases

Information in the Table

4 7 Silve r

Ag 107.87

Atomic number Name of the element Elemental Symbol

Atomic mass (weight)

• 109 elements are currently known: – 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.