7. Periodicity

Question 1

What are the key properties of Group 1 elements (alkali metals)?

Answer 1

Metals with low density (the first three are less dense than water)

React with non-metals to form ionic compounds with a +1 charge

Compounds are white solids that dissolve in water to form colorless solutions

React with water, releasing hydrogen

Form hydroxides that dissolve in water to give alkaline solutions

Question 2

How does reactivity change in Group 1?

Answer 2

The further down the group, the more reactive the element.

Question 3

Why does reactivity increase going down Group 1?

Answer 3

Reactivity increases down Group 1 because the outer electron is farther from the nucleus due to additional energy levels.

This increased distance reduces the electrostatic attraction between the nucleus and the outer electron.

Consequently, the outer electron is more easily lost, making the element more reactive.

Question 4

What are the key properties of Group 7 elements (halogens)?

Answer 4

React with metals to form ionic compounds where the halide ion carries a charge of –1

The further down the group, the less reactive the element

Higher melting and boiling points as you go down the group

Question 5

How does reactivity change in Group 7?

Answer 5

The further down the group, the less reactive the element.

Question 6

Why does reactivity decrease going down Group 7?

Answer 6

Reactivity decreases down Group 7 because the outer electrons are farther from the nucleus as additional energy levels are added.

This increased distance reduces the electrostatic attraction between the nucleus and the incoming electron.

As a result, it becomes harder for the element to gain an additional electron, making it less reactive.

Question 7

What can a more reactive halogen do to a less reactive halogen in an aqueous solution of its salt?

Answer 7

A more reactive halogen can displace a less reactive halogen.

Question 8

Where are transition metals located on the periodic table?

Answer 8

In the center of the periodic table between Groups 2 and 3.

Question 9

What are some characteristics of transition metals?

Answer 9

Have ions with different charges

Form colored compounds

Are useful as catalysts

Question 10

How do transition metals compare with Group 1 elements?

Answer 10

Have higher melting points (except mercury) and higher densities

Are stronger and harder

Are much less reactive and do not react as vigorously with water or oxygen