Shapes, IE

Question 1

What are the angles around a tetrahedral molecule

Answer 1

109.5 degrees. For every lone pair this is decreased by 2.5 degrees due to electron repulsion.

Question 2

What is electronegativity

Answer 2

The ability of an atom to attract the bonding electrons in a covalent bond. It is measured on the Pauling scale, with a higher number meaning a greater electronegativity.

Question 3

Why are periods used in the periodic table

Answer 3

Elements in the same period show repeating trends in physical and chemical properties - this is called periodicity.

Question 4

What properties do elements in the same groups have in common

Answer 4

The same chemical properties

Question 5

Define first ionisation energy

Answer 5

The enthalpy change that occurs when an electron is removed from each of one mole of gaseous atoms to form one mole of 1+ gaseous ions.

Question 6

What are the general rules for predicting IE trends

Answer 6

When moving between main shells, there will always be a massive increase in IE. Removing electrons from repelling pairs will often mean a smaller increase in IE. Moving between subshells means removing electrons from a full subshell, this will cause an increase in IE. IE will decreases the greater the atomic number as there is more shielding.

Question 7

Why is there an increase in first ionisation energy between F and Ne?

Answer 7

• Nuclear charge increases
• Same shielding
• Greater nuclear attraction

Question 8

Why is there a decrease in first ionisation energy between Ne and Na?

Answer 8

• One more shell
• More shielding
• Less nuclear attraction