Atomic Structure

Question 1

Atomic Number (Z)

Answer 1

defines an element- no. protons

Question 2

Mass Number (A)

Answer 2

no. protons + electrons

Question 3

define isotope

Answer 3

different atoms of same element w/ same no. protons, diff no. neutrons

Question 4

describe properties of isotopes of an element:

Answer 4

same chemical properties bc chemical properties depend on no. electrons but diff. physical properties bc depend on mass no.

Question 5

relative atomic mass

Answer 5

average of all naturally occurring isotopes of an element relative to 1/12 of mass of carbon-12

Question 6

what is mass spectrometer

Answer 6

measures proportions of each isotope present in a sample of an element in its vaporized state

Question 7

greater deflection in a mass spectrometer=

Answer 7

higher charge and lower mass

Question 8

how are electrons arranged in an atom

Answer 8

in energy levels

Question 9

max no. electrons in an energy level

Answer 9

2n squared

Question 10

describe the emission spectrum of H

Answer 10

a line spectrum w/ only certain frequencies/ wavelengths of light present- lines converge at a higher frequency/ energy

Question 11

evidence for electrons being in energy levels

Answer 11

the emission spectrum because each line occurs when an excited electron falls back to its ground state bc unstable (when energy supplied to atom = excited from ground state - higher energy level), releasing E which corresponds to a particular wavelength that shows up as a line in the spectrum

Question 12

A jump to n=1

Answer 12

ultraviolet spectrum bc highest E

Question 13

a jump to n=2

Answer 13

visible spectrum

Question 14

define convergence limit

Answer 14

when lines merge to form a continuum- beyond this point electron can have any E + free to leave atom

Question 15

define orbital

Answer 15

region of space w/ high probability of finding an electron- represents discrete E level

Question 16

Pauli Exclusion principle

Answer 16

max no. electrons in an orbital=2 + electrons must have opposite spins

Question 17

Hunds Rule

Answer 17

orbitals must be filled singly first

Question 18

ionisation energy

Answer 18

minimum amount of energy required to remove an electron from an atom of an element in its gaseous state

Question 19

describe relationship between energy of a photon and frequency of electromagnetic radiation

Answer 19

E = hv

Energy (J)= frequency of light x Planck’s Constant = 6.63 x 10-34)

Question 20

how to work out wavespeed

Answer 20

wavespeed = frequency x wavelength

Question 21

why is second ionisation E always higher than the first?

Answer 21

once 1 electron removed = +ve ion which attracts electrons more strongly than neutral atoms therefore more E required to remove it

when 1 electron = removed, less e-e repulsion therefore electrons pulled in closer to nucleus= strongly attracted and difficult to move

Question 22

how does ionisation E change across and period and why?

Answer 22

ionisation E increases along a period bc:

• nuclear charge increases
• electrons all removed from same energy level so no change in electron shielding
• attractive force on electrons increases from left to right

Question 23

why does boron have a higher ionisation energy than beryllium?

Answer 23

electron removed from boron atom = in 2p sublevel which is at a higher energy than 2s so less energy required to remove it

Question 24

why does nitrogen have a higher ionisation energy than oxygen?

Answer 24

nitrogen has 3 electrons in the 2p orbital whilst O has 4 in 2p orbital. Therfore there is pair of electrons in the 2p of oxygen. These electrons repel each other so electron = easier to remove

Question 25

why does ionisation energy decrease down a group?

Answer 25

shielding of outer electrons from nucleus so attraction is weaker and are more easily removed

Question 26

how to do electronic configurations for transition metals:

Answer 26

fill in 4s subshell first. for ions, remove 4s electrons first. copper and chromium only have 1 electron in 4s subshell bc atoms = most stable when subshell= full or half full

Question 27

arrange subshells in order of increasing energy:

Answer 27

s, p,d,f