1.2 basic ideas about atoms

Question 1

what is an alpha particle?

Answer 1

a helium nucleus; 2 protons and 2 neutrons.

Question 2

what electric plate is an alpha particle attracted to?

Answer 2

the negative plate.

Question 3

what direction does a magnetic field deflect an alpha particle to?

Answer 3

in a certain direction.

Question 4

what is the penetrating and ionising power of an alpha particle and how is it stopped?

Answer 4

it is the least penetrating but the most ionising; it is stopped by a piece of paper.

Question 5

what is a beta particle?

Answer 5

a high energy, fast moving electron.

Question 6

what electric plate is a beta particle attracted to?

Answer 6

the positive plate.

Question 7

what direction does a magnetic field deflect a beta particle to?

Answer 7

in the opposite direction.

Question 8

what is the penetrating and ionising power of a beta particle and how is it stopped?

Answer 8

it is weakly penetrating and ionising; it is stopped by a thin sheet of metal such as aluminium foil.

Question 9

what is a gamma ray?

Answer 9

high energy electromagnetic radiation.

Question 10

what electric plate is a gamma ray attracted to?

Answer 10

an electric field has no effect on a gamma ray.

Question 11

what direction does a magnetic field deflect a gamma ray to?

Answer 11

a magnetic field has no effect on a gamma ray.

Question 12

what is the penetrating and ionising power of a gamma ray and how is it reduced?

Answer 12

it is the most penetrating but weakly ionising; it is reduced by a few cm of lead.

Question 13

when an element emits an alpha particle, how much does the mass number and atomic number decrease by?

Answer 13

the mass number decreases by 4, the atomic number decreases by 2.

Question 14

when an element emits an alpha particle, where is the new product in the periodic table?

Answer 14

it moves 2 places to the left.

Question 15

when an element emits a beta particle, how much does the mass number and atomic number increase by?

Answer 15

the mass number stays the same, the atomic number increases by 1.

Question 16

when an element emits a beta particle, where is the new product in the periodic table?

Answer 16

it moves 1 place to the right.

Question 17

what is electron capture?

Answer 17

the inverse of beta decay; one of the orbital electrons is captured by a proton in the nucleus forming a neutron and emitting an electron neutrino.

Question 18

in electron capture, how much does the mass number and atomic number decrease by?

Answer 18

the mass number stays the same, the atomic number decreases by 1.

Question 19

in electron capture, where is the new product in the periodic table?

Answer 19

it moves 1 place to the left.

Question 20

what is positron emission?

Answer 20

a proton is converted to a neutron and a positron and electron neutrino are released.

Question 21

in positron emission, how much does the mass number and atomic number decrease by?

Answer 21

the mass number stays the same, the atomic number decreases by 1.

Question 22

in positron emission, where is the new product in the periodic table?

Answer 22

it moves 1 place to the left.

Question 23

how do electrons fill atomic orbitals?

Answer 23

in order of increasing energy.

Question 24

how many electrons can fit in an orbital?

Answer 24

2.

Question 25

what property must 2 electrons have in order to exist in the same orbital?

Answer 25

they must spin in opposite directions.

Question 26

what are the 2 exceptions when writing electronic configuration?

Answer 26

chromium and copper.

Question 27

what is the electronic configuration of chromium and why?

Answer 27

1s2 2s2 2p6 3s2 3p6 4s1 3d5. 3d borrows an electron from 4s to become more stable; it needs at least 1 electron in each orbital.

Question 28

what is the electronic configuration of copper and why?

Answer 28

1s2 2s2 2p6 3s2 3p6 4s1 3d10. 3d borrows an electron from 4s to become more stable; it needs at least 1 electron in each orbital.

Question 29

why does the 4s orbital fill up before 3d?

Answer 29

the 4s orbital is of a lower energy level.

Question 30

what is first ionisation energy?

Answer 30

the energy required to remove 1 mole of electrons from 1 mole of gaseous atoms to form 1 mole of gaseous 1+ ions.

Question 31

what is second ionisation energy?

Answer 31

the energy required to remove 1 mole of electrons from 1 mole of gaseous 1+ ions to form 1 mole of gaseous 2+ ions.

Question 32

what is the equation for first ionisation energy?

Answer 32

X(g) -> X+(g) + e-.

Question 33

how does atomic radius affect ionisation energy?

Answer 33

the greater the atomic radius, the smaller the attractive force on the outer electron, so it is easier to remove.

Question 34

how does nuclear charge affect ionisation energy?

Answer 34

electrons are attracted to the protons in the nucleus. the greater the number of protons, the greater the attractive force between the outer electron and nucleus, so it is harder to remove.

Question 35

how does electron shielding affect ionisation energy?

Answer 35

outer shell electrons are repelled by inner shell electrons. the more filled inner shells/subshells there are, the smaller the attractive force on the outer electron.

Question 36

if the attractive force between the nucleus and outer electron is small, is it easier or harder to remove an electron?

Answer 36

easier.

Question 37

if the attractive force between the nucleus and outer electron is large, is it easier or harder to remove an electron?

Answer 37

harder.

Question 38

why do successive ionisation energies always increase? (nuclear charge)

Answer 38

there is a greater nuclear charge as the same number of protons is holding fewer and fewer electrons.

Question 39

why do successive ionisation energies always increase? (electron shielding)

Answer 39

as each electron is removed, there is less electron-electron repulsion and each shell will be drawn slightly closer to the nucleus.

Question 40

why do successive ionisation energies always increase? (atomic radius)

Answer 40

as the distance of each electron from the nucleus decreases, the nuclear attraction increases.

Question 41

what is absorption spectra?

Answer 41

when white light is passed through the vapour of an element, certain wavelengths will be absorbed by the atoms and removed from the light.

Question 42

what colour lines do you see on an absorption spectrum?

Answer 42

black lines will appear in the spectrum where light of some wavelengths has been absorbed.

Question 43

what do the wavelengths in an absorption spectra correspond to?

Answer 43

the energy taken in by the atoms to promote electrons from lower to higher energy levels.

Question 44

what is emission spectra?

Answer 44

when atoms are given energy by heating or an electrical field, electrons are promoted to a higher energy level. when the source of energy is removed, electrons in the excited state fall back to their ground energy level.

Question 45

what colour lines would you see on an emission spectrum?

Answer 45

coloured lines on a black background.

Question 46

why does the hydrogen spectrum consist of many seperate series of lines?

Answer 46

transitions between different energy levels result in the emission of radiation of different frequencies. this produces different lines.

Question 47

what is the paschen series and in what region is it located?

Answer 47

the paschen series is in the infrared region. each line is due to electrons returning to the 3rd shell or n=3 energy level.

Question 48

what is the balmer series and in what region is it located?

Answer 48

the balmer series is located in the visible section. each line is due to electrons retuning to the 2nd shell or n=2 energy level.

Question 49

what is the lyman series and in what region is it located?

Answer 49

the lyman series is located in the ultraviolet region. each line is due to electrons returning to the 1st shell or n=1 energy level.

Question 50

what is the convergence limit?

Answer 50

when the frequency of spectral lines increases to the point they cannot be distinguished.

Question 51

what series represents the ionisation of a hydrogen atom?

Answer 51

the convergence limit in the lyman series.