Periodic Table: Trends and Properties

Question 1

Modern periodic table

Answer 1

Arranged elements in order of increasing atomic number
Metals are good conductors of heat and electricity
Show variety in chemical properties
Similarities between physical and chemical properties in group (vertical)

Question 2

Effective Nuclear charge

Answer 2

The nuclear charge felt by the electron when both the actual nuclear charge and the repulsive effect of the other electrons are taken into account

Question 3

Atomic radius

Answer 3

Half the distance between the nuclei of 2 adjacent atoms

Question 4

Atomic radius across a period

Answer 4

Decreases 
Increasing atomic no. 
Increasing no. protons in nucleus
Adding e- to same energy level
Increase of effective nuclear charge
Bigger attraction

Question 5

Atomic radius down a group

Answer 5

Increase
Electrons enter another energy level
Greater distance between nucleus and outermost shell

Question 6

Ionic radius

Answer 6

Radius of a cation or anion

Question 7

Formation of an anion

Answer 7

Formation of anion 
Addition of electron
Nuclear charge remains the same
Greater repulsion amongst electrons 
Size increases

Question 8

Formation of cation

Answer 8

Less electrons
Nuclear charge remains the same
Less repulsion amongst electrons
Size decreases

Question 9

Effective nuclear charge down a group

Answer 9

Effective nuclear charge increases
Valence electrons go into additional shell
Different orbitals have different shielding ability
Slaters rules calculates sigma by accounting for the effective shielding of electrons in each orbital shell

Question 10

Effective nuclear charge across a period

Answer 10

Increases
Extra proton and electron is a valence electron which doesn’t shield itself well
Increased force of attraction

Question 11

which would have a stronger pulling power and why? Dipositive ion or unipositive ion?

Answer 11

Dipositive ion because it has protons to pull electrons closer.

Question 12

Ionisation energy

Answer 12

The minimum energy required to remove an electron from a gaseous atom in its ground state.

Question 13

Ionisation energy across a period

Answer 13

Increases
Nuclear charge is increased 
Adding e- to same energy level
Effective nuclear charge increases
Bigger attraction - harder to remove

Question 14

Ionisation energy down a group

Answer 14

Decreases
Electrons enter another energy level
Greater distance between nucleus and outermost shell
Weakens nuclear attraction in outermost e-. Easier to remove

Question 15

Electronegativity

Answer 15

the measure of the ability of an atom in a bond to attract

electrons to itself.

Question 16

Electronegativity down a group

Answer 16

the number of energy levels (n) increases, and so does the distance between
the nucleus and the outermost orbital. The increased distance and the increased
shielding weaken the nuclear attraction, and so an atom can’t attract electrons as strongly.

Question 17

Electronegativity across a period

Answer 17

valence shells are less than half full, so these atoms (metals) tend
to lose electrons and have low electronegativity. Towards the right of the table,
valence shells are more than half full, so these atoms (nonmetals) tend to gain electrons and
have high electronegativity.

Question 18

Electron affinity

Answer 18

the negative of the energy change that occurs when an electron is accepted by an atom in the gaseous state to form an anion.

Question 19

the more positive the electron affinity of an element

Answer 19

the greater is the affinity of an atom of the element to accept an electron.

Question 20

The electron affinity across a period

Answer 20

Becomes more negative