Electronic Structure of Atoms

Question 1

Energy levels and sub-levels

Answer 1

A measure of the amount of energy possessed by an electron when it is in an atom. All electrons in the same shell have the same energy. main levels of atoms possess sublevels of energy.
The sublevels include the four types s( sublevels contain up to 2 e-),p(sublevels contain u to 6e-),d and f

Question 2

quantum mechanical model

Answer 2

electrons don’t have a position we can track. Instead
electrons can be found in clouds. clouds are regions of probability where electrons can be found. The denser cloud the greater the probability of the electron being there.

Question 3

orbital

Answer 3

The region in space around the nucleus of an atom in which the electrons are most likely to be found

Question 4

Bohr Models of Atoms in the Periodic Table (across, down)

Answer 4

Across a period : the number of shells is constant
“ valence electrons increases
“ protons increases

Down a group : the number of shells increases
“ valence electrons is constant
“ protons increases

Question 5

nuclear charge

Answer 5

valence electrons are attracted to the positive charge of the nucleus and repelled by the negative charges of other electrons.
The more protons that are in the nucleus, the stronger the attraction between the nucleus and the outer electrons.

Question 6

shielding effect

Answer 6

electrons in the inner shells help to weaken the force of attraction between the nucleus and the electrons in the outer shell.

The shielding effect stays constant across a period as the number of shells and hence number of inner electrons stays constant.

The shielding effect increases down a group as the number of shells and hence number of inner electrons increases.

Question 7

Atomic Radius

Answer 7

one-half distance between the nuclei of two atoms of the same element when the atoms are joined

A larger atomic radius means that valence electrons are less attracted towards the nucleus
A smaller atomic radius means that stronger attraction between the valence electrons and the nucleus.

Question 8

Atomic Radius trends

Answer 8

Atomic radius decreases across a period as increasing nuclear charge and no increase in shielding effect. - stronger attraction

Atomic radius increases down a group as new shells and shielding effect increases. - help to weaken the force of attraction between nucleus and valence electron.

Question 9

Ionic Radius - cation, anion

Answer 9

cation - the radius of the atom gets smaller - greater nuclear charge - the ratio of protons to electrons is going to increase
anion - the radius of the atom gets bigger

Question 10

1st ionisation enrgy

Answer 10

The energy required to remove one more of valence electron

Question 11

Why 2nd ionisation needs more energy than 1st ionisation on sodium?

Answer 11

bc it is easier to remove an electron when 1st ionisation rather than 2nd one.

Question 12

Trends in ionisation energy

Answer 12

Ionisation energy increases across a period because of increasing nuclear charge and decreasing atomic radius

Ionisation evergy decreases down a group as increasing atomic radius and shielding effect increases

Question 13

Give 3 reasons why ionisation energy decreases down a group?

Answer 13

atomic radius increases
the number of shells increases
the distance between nucleus and valence e- increases