Trends

Question 1

The atomic radius

Answer 1

the atomic radius of an element is half the distance between the nuclei of two atoms of that element when bonded to a single covalent bond

Question 2

The atomic radii decrease across a period (→) in the periodic table due to:

Answer 2

• increase in effective nuclear charge - the electrons in the outer shell are pulled closer to the increasingly positive nucleus whilst the no. of inner shells remains the same across the period
• no increase in shielding effect - same no. of shells across a period

Question 3

The atomic radii increase down a group (↓) due to:

Answer 3

• increase in the no. of shells (moving down a group a new shell is added) which increases the shielding effect - additional inner shells of electrons shield the outer electrons from the positive nucleus

Question 4

Positive ions

Answer 4

• smaller than the original atom
• the positively charged nucleus has less electrons to pull on so electrons are pulled closer

Question 5

Negative ions

Answer 5

• larger than the original atom
• the gain in electrons and no increase in charge means that the outer electrons are held more loosely

Question 6

First ionisation energy

Answer 6

• the minimum energy required to remove the most loosely held electron from one mole of gaseous atoms in their ground state #- measured in kJmol-1

Question 7

Ionisation energy values increase across a period due to:

Question 8

Ionisation energy values decrease down a group due to:

Question 9

How to explain trends in ionisation energy values within a particular element/ How jumps in ionisation energy values provide evidence for the existence of energy values

Answer 9

1.
2.
3.

Question 10

Electronegativity

Answer 10

the relative attraction that an atom in a molecule has for the shared pair of electrons in a single covalent bond