Chemistry - The Periodic Table

Question 1

What are Group 1 elements?

Answer 1

Lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr). They are ALKALI metals.

Question 2

What are the physical properties of Group 1 elements?

Answer 2

• Soft, can be cut easily (due to weak metallic bonds)
• Low melting and boiling points
• Low densities (remember that density = mass/volume!)
• Lithium, sodium and potassium float on water

Question 3

What are the trends in properties across Group 1 elements?

Answer 3

Going DOWN the group, the melting points DECREASE, the densities INCREASE, the number of shells (size of atom) INCREASES, reactivity INCREASES.

Question 4

Why do metals have higher melting points?

Answer 4

Stronger metallic bonds –> higher melting point. The delocalised electrons will be more strongly attracted to the metal cations –> more energy needed to break the metallic bonds –> higher melting point.

Question 5

What are the chemical properties of Group 1 elements?

Answer 5

• Highly reactive, stored in oil to prevent from reacting with air and water
• Have 1 valence electron (lose 1 to be a noble gas)
• Reaction with water:
  - Lithium reacts quickly and floats on water
  - Sodium reacts violently (may be explosive) and darts around the water surface
  - Potassium reacts very violently (explosive)
• Reacts vigorously with cold water

Question 6

Why do some metals have high reactivity?

Answer 6

The more shells an atom has, the easier it is to lose the outermost electron, making it more reactive.

Question 7

What are Group 17 metals?

Answer 7

Fluorine (F), chlorine (Cl), bromine (Br), iodine (l), astatine (At), and tennessine (Ts). They are called HALOGENS.