Chapter 2-Atomic structure

Question 1

A

Answer 1

Mass #

Question 2

Z

Answer 2

Atomic #

Question 3

Anions

Answer 3

Gain (e-) to become negative (-)

Question 4

Cations

Answer 4

Lose (e-) to become positive (+)

Question 5

Isotopes

Answer 5

Atoms with the same # of protons and electrons but diff # of neutrons

Have similar chem properties (cuz it’s valence electrons that determine chem prop)

Question 6

Ar (Relative atomic Mass)

Answer 6

(% Abundance)(mass)+…+…/100

Question 7

How can Radioisotopes be made?

Answer 7

Exposing the natural element to flux of slow moving neutrons in nuclear reactor.
(Nucleus captures EXTRA neutron!)

Question 8

Radioactive tracers rely on?

Answer 8

Fact that radioisotopes behave chemically (& biologically) the SAME as stable isotopes.

Question 9

Nuclear Medicine (Thyroid glands % Iodine)

Answer 9

• Thyroid glands=absorbs iodine
• Activity can be measured by monitoring the increase in radioactivity of glands after taking drink containing traces of radioactive iodine [I(125) or I(131)]
• PET scanners detect abnormalities s.a growth of tumour etc.

Question 10

Atomic Spectra (by decreasing Freq)

Answer 10

Radio waves/ Microwaves/ IR light/ Vis. L/ UV light/ X-rays/ gamma rays

Question 11

Blue light has more____than red light

Answer 11

Energy

Question 12

When an atom is excited by what happens to electrons?

Answer 12

The electrons gain energy and move to a higher energy level.

Question 13

If atom excited by light what happens?

Answer 13

Light of particular wavelength corresponding to the Activation Energy = ABSORBED= leaves a black line in the continuous spectrum. (LINE ABSORPTION SPECTRUM)

Question 14

What happens when electrons return to lower energy?

Answer 14

It must LOSE energy! By emitting light of a particular frequency = LINE EMISSION SPECTRUM

Question 15

Equation of amt of energy lost by electron

Answer 15

Change in energy= (h)(v)
Where:
h = Plank’s constant = 6.63*10^-34 J
v = Frequency

Question 16

Velocity equation

Answer 16

c = (v)(lambda)
c = Velocity in vacuum (3*10^-8 m/s)

Question 17

What happens to the lines in the spectrum as freq increases?

Answer 17

They will converge. Cuz the higher the energy level = the smaller the difference in energy between successive energy levels.

Question 18

What is the limit of the convergence of the lines in the emission spectrum?

Answer 18

The energy required to completely remove the electron from the atom = IONISATION ENERGY

Question 19

What does each series in an emission spectrum correspond to?

Answer 19

It corresponds to the transitions in which the electrons fall to a particular energy level.

Question 20

Lyman series region of light

Answer 20

UV

Question 21

Balmer series region of light

Answer 21

Visible light

Question 22

Pauli exclusion principle

Answer 22

No 2 electrons in an atom can be in exactly the same state.

Question 23

How many orbitals does the s,p,d sub-levels each contain?

Answer 23

s = 1
p = 3
d = 5

Question 24

How many electrons does the s,p,d sub-levels each contain?

Answer 24

s = 2
p = 6
d = 10

Question 25

‘Aufbau’ principle

Answer 25

Electrons in atoms ALWAYS adapt the lowest energy configuration possible. By filling in one sub-level COMPLETELY before the next.

Question 26

Hund’s Rule

Answer 26

Sub-level orbitals are singly occupied as far as possble by electrons in the same spin.

Question 27

Exceptions to the filling of 3d and 4s orbitals

Answer 27

When there’s a possibility of the 3d sub-level to be HALF or FULLY filled = takes PRIORITY over completely filling 4s sub-level.

Question 28

Ionisation energy

Answer 28

The min amt of energy required to remove a mole of electrons from a mole of gaseous ATOMS to from a mole of gaseous IONS. (CATIONS)

Question 29

Is Ionisation every exothermic or endothermic?

Answer 29

Exothermic.

Energy needed to remove negatively charged electrons from attraction of positively charged nucleus.

Question 30

The charge on the nucleus of an atom is counteracted by? (3 things)

Answer 30

1. Repulsion
2. “Shielding” of electrons in filled inner orbitals
3. Repulsion from other electrons in valence shell.

Question 31

Effective Nuclear Charge (ENC)

Answer 31

The remaining nuclear charge in each energy level when the total nuclear charge is subtracted by the electrons in the different shells.

Question 32

Why use the log scale for Ionisation energy?

Answer 32

Makes shell structure more obvious cuz if linear scale was used ALL the 1st ten ionisation energies would be v. close together.

Question 33

Why is there a steady increase of successive ionisation energy for every element?

Answer 33

As more electrons removed = decrease in the electron-electron repulsion betw. electrons in valence shell.

Question 34

What happens to ionisation energy going across a period?

Answer 34

Steady increase. cuz increase of nuclear charge of atoms within an energy level. As the electrons are added to the same energy level.

Question 35

What happens to the ionisation energy going down a group.

Answer 35

Decreases.
Effective nuclear charge = relatively constant (extra nuclear charge = cancelled out by an extra filled electron shell)
Electrons lost = in successively higher energy level = further from nucleus.

Question 36

Isoelectrons

Answer 36

Species that have the same electronic structure.