Electron configuration

11

NaSodium

E.C= 2.8.1

2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8

2.8.1 2.8.4 2.8.5 2.8.6 2.8.7 2.8.82.8.2 2.8.3

2.8.8.1 2.8.8.2

1 2

Group 1

Group2

Group 13

Group 14

Group 15

Group 16

Group 17

Group 18

Period 1

Period 2

Period 3

Period 4

1 2

3 4 5 6 7 8 9 10

11 12 13 14 15 16 17 18

19 20

Group• For elements with 1 to 2 valence electrons

Group number of element= the number of valence electrons

• For element with 3-8 valence electrons,

Group number of element= the number of valence electrons +10

Period

• The period number of an element = the number of shells occupied with electrons

Arrangement of elements

a) A group is a vertical column.b) 8 groups ( all the elements in a group have

almost the same chemical properties and slightly different physical properties ) Group 1 – alkali metal Group 2 – alkali earth metal Group 17 – halogen Group 18 – noble gas

c) Biggest group – transition metalsd) Horizontal row is a period.

e) Arrange according their proton number

f) Elements with similar properties are arranged in groups.

g) The electrons in the outer most orbit of an atom are called the valence electrons.

h) All the elements in the same group have the same number of valence electrons.

First person to write the list consists of 33 elements.

Classified element into 4 groups.

•Metals

•non-metals

Classified elements into groups of 3 with similar chemical properties(triads)

Chemical properties

Atomic mass

Element in the triad Relative atomic mass

Lithium 7

Sodium 23

Potassium 39

• Arranged known elements into increasing atomic mass order.

• Plot a graph of atomic volume vs atomic mass.

• Showed that the properties of elements were in a periodic pattern with their atomic mass.

• Arranged the elements with similar chemical

properties into groups.• Left empty spaces for element

which have yet to be discovered.

• Studied the X-ray spectrum.

• Determine the proton number

• Rearranging the elements in

order of increasing proton

number

•Andy lau’s Dog

Jump, Lorry Men

Happy

Remember the 20 elements of

periodic table

H He

Little Belly Boy Come Near Oreo For Nutrition

Naughty Man And Silly People Should Consume A lot of

Kentucky Combo

GROUP 18The Noble Gases

Group 18 Elements

1. Noble gas

2. Make up almost 1% of the air

3. There are helium, neon, argon, krypton, xenon, radon.

4. All the noble gases do not:

Dissolve in water

Conduct electricity

Conduct heatstable

Group 18 Elements

5. Monoatomic gases at room temperature

6. All the noble gases have low m.p and low b.p. It is due to their very weak intermolecular force of attraction. (Van der Waals).

7. Boiling point, b.p increases down the group

8. Melting point, m.p increases down the group

9. Very low density ( weak intermolecular forces).

10.Density increases down the group. (relative atomic mass increase more than volume.

Elements Radius M.p B.p Density

He

Ne

Ar

Kr

Xe

Rn

DOWN THE GROUP

Inert property

1. Low reactivity. 2. Exist as monoatoms.3. Helium has 2 electrons in the outer most shells.

(duplex electron configuration)4. Other noble gases have 8 electrons in their outer

most shells. (octet configuration)5. All the outer most shells are fully filled. (stable)6. They do not accept anymore electrons. Do not donate Do not accept Do not share

Helium

• Helium is less dense than air, so it’s great for all kinds of balloons.

Group 18—Helium

Mixed with oxygen for deep sea

diving

Fill up balloons and air ships

Neon

• Used in advertisement boards

Group 18—Neon

Argon

• To fill light bulbs to prevent the filament from burning

Group 18—Argon

• To fill photographic flash lampsGroup 18—Krypton

• Used in the brightest bulb in lighthouse.

Group 18- Xenon

Radon• Used in cancer

treatment

Weekend assignment

• Look though Group 1 (Alkali Metals)