2.2- trends in the periodic table Pt1

Question 1

what is the core charge?

Answer 1

core charge of atom is a measure of the attractive force felt by the valence shell electrons towards the nucleus

Question 2

how to find the core charge

Answer 2

core charge = number of protons - total inner shell electrons

Question 3

trend in core charge down a group

Answer 3

remains constant

core charge stays constant down a group, but the valence electrons are held less strongly as they are further from the nucleus (there are more shells in the atom)

Question 4

trend in core charge left to right across a period

Answer 4

increases

valence electrons are more attracted to the nucleus as the core charge increases

Question 5

what is electronegativity

Answer 5

the ability of an atom to attract electrons towards itself.

the more strongly the valence electron of an atom are attracted to the nuclus of the atom the greater the electronegativity.

Question 6

trend in electronegativity down a group

Answer 6

decreases

core charge stays constant and number of shells increase down a group

therefore valence electrons are less strongly attracted to the nucleus as they are further from the nucleus (result = electronegativity decreases)

Question 7

trend in electronegativity left to right across a period

Answer 7

increases

number of occupied shells remain constant
but core charge increases across a period
= valence electrons = strongly attracted to nucleus = increase in electronegativity

Question 8

atomic radius

Answer 8

measurement used for the size of an atom.

• regarded as the distance from nucleus to valence shell electrons
• measured by halving the distance from the nuclei of two atoms of the same element that are bound together

Question 9

trend in atomic radii down a group

Answer 9

increases

• core charge stays constant, number of shell increases

Question 10

trend in atomic radii left to right across a period

Answer 10

decreases

• number of occupied shell in atom remains constant
• core charge increases
• valence electrons become strongly attracted to nucleus