Periodicity

Question 1

When testing for sulphate ions, what would be present when white ppt, cream ppt and yellow ppt are produced?

Answer 1

White ppt - silver chloride
Cream ppt - silver bromide
Yellow ppt - silver iodide

Question 2

What does the periodic table provide chemists with?

Answer 2

A structured organisation of the known chemical elements from which they can make sense of their physical and chemical properties.

Question 3

What does the historical development of the periodic table and models of atomic structure provide?

Answer 3

Good examples of how scientific ideas and explanations develop over time.

Question 4

What is a group?

Answer 4

A vertical column of elements with similar properties.

Question 5

What happens to atomic radii going across a period?

Answer 5

It decreases.

Question 6

Why does atomic radii change going across a period?

Answer 6

Nuclear charge increases, meaning electrons are more greatly attracted to the nucleus.

Question 7

What is the trend in first ionisation energy going across a period?

Answer 7

Increases going across a period.

Question 8

What causes the change in first ionisation energy going across a period?

Answer 8

Due to the increasing charge on the nucleus and the increasing number of electrons in the main level, the electrostatic forces of attraction become stronger, so it becomes harder to remove an electron.

Question 9

Why is there a drop in ionisation energy from one period to the next?

Answer 9

There’s a new main level, so atomic radius increases meaning the electron is further away from the nucleus.

Question 10

Why does first ionisation energy decrease going down the group?

Answer 10

Shielding increases and the distance between the nucleus and the electron that’s being removed.