JCE LMS - Elements and the Periodic Table

Elements and the Periodic Table

Learning Objectives

Understand periodic trends
Classify elements by groups
Analyze chemical properties
Conduct virtual experiments

Key Classifications

Metals

Non-metals

Metalloids

Interactive Periodic Table Preview

Li

3

Ne

10

Na

11

Mg

12

Cl

17

Ar

18

Alkali Metals Alkaline Earth Halogens Noble Gases

Periodic Trends

Atomic Radius

The distance from the nucleus to the outermost electrons.

↓ Increases down a group (more energy levels)

→ Decreases across a period (stronger nuclear charge)

Example: Group 1

Li < Na < K (increasing atomic radius)

Ionization Energy

Energy required to remove an outermost electron.

↓ Decreases down a group (electrons further from nucleus)

→ Increases across a period (stronger attraction)

Inverse Relationship

As atomic radius increases, ionization energy decreases

Electronegativity

Ability to attract shared electrons in a bond.

↓ Decreases down a group

→ Increases across a period

Electron Affinity

Energy released when an atom gains an electron.

↓ Generally decreases down a group

→ Generally increases across a period

Group I - Alkali Metals

Li

Lithium

Atomic Number: 3

Scarlet flame color

Na

Sodium

Atomic Number: 11

Yellow flame color

K

Potassium

Atomic Number: 19

Lilac flame color

Physical Properties

Soft metals (can be cut with knife)
Low melting and boiling points
Shiny when freshly cut
Low density (float on water)
Good conductors of heat and electricity

Chemical Properties

Highly reactive (stored in oil)
Form +1 ions easily
React vigorously with water
Tarnish quickly in air
Reactivity increases down the group

Group II - Alkaline Earth Metals

Be

Beryllium

Atomic Number: 4

Mg

Magnesium

Atomic Number: 12

Ca

Calcium

Atomic Number: 20

Sr

Strontium

Atomic Number: 38

Key Characteristics

Form +2 ions
Higher melting points than alkali metals
Less reactive than Group I
Reactivity increases down the group

Common Uses

Mg: Lightweight alloys, pharmaceuticals
Ca: Cement production, antacids
Be: X-ray applications, aerospace

Group VII - Halogens

F

Fluorine

Gas - Pale yellow

Cl

Chlorine

Gas - Pale green-yellow

Br

Bromine

Liquid - Deep red

I

Iodine

Solid - Dark purple

Uses of Halogens

Fluorine Uses

• Toothpaste (prevents decay)
• Plastics manufacturing
• Refrigeration systems

Chlorine Uses

• Water treatment
• PVC production
• Bleaching agents

Bromine Uses

• Photography
• Flame retardants
• Anti-knock agents

Iodine Uses

• Medical disinfectant
• Table salt additive
• Starch testing

Group VIII - Noble Gases

He

Helium

Balloons, cooling

Ne

Neon

Advertising signs

Ar

Argon

Light bulbs, welding

Unique Properties

Fully filled outer electron shells

Very unreactive (inert)

Exist as monoatomic gases

Do not conduct electricity

Atomic size increases down group

Colorless and odorless

Virtual Experiments

Experiment 1.3: Alkali Metals with Water

Aim: Investigate reactions of Li, Na, K with water

🧪 Materials: Glass trough, tongs, universal indicator

⚠️ Safety: Use tongs, observe from distance

Experiment 1.4: Alkali Metals with Chlorine

Aim: Observe reactions of Li, Na with chlorine gas

🧪 Materials: Deflagrating spoon, chlorine jars

⚠️ Safety: Use fume cupboard, avoid K reaction

Experiment 1.5: Alkaline Earth with Air

Aim: Compare Mg and Ca reactions with oxygen

🧪 Materials: Mg ribbon, Ca granules, Bunsen burner

⚠️ Safety: Don't look directly at burning Mg

Halogen Reactivity Test

Aim: Compare halogen reactivity with metals

🧪 Materials: Various metals, halogen solutions

⚠️ Safety: Handle halogens with care