atomic structure & periodic table

Question 1

define atomic number

Answer 1

the number of protons in the nucleus of an atom of that element

Question 2

define mass number

Answer 2

the number of protons + number of neutrons

Question 3

define isotopes

Answer 3

isotopes are atoms of the same element with the same number of protons but a different number of neutrons
(same number of electrons)

Question 4

define relative atomic mass

Answer 4

the weighted mean mass of an atom of an element compared to the mass of 1/12th of a carbon 12 atom

Question 5

define relative molecular mass

Answer 5

weighted mean mass of a molecule compared to the mass of 1/12th of a carbon 12 atom

Question 6

define relative formula mass

Answer 6

the mean weighted mass of a formula unit compared to the mass of 1/12th of a carbon 12 atom

Question 7

what is the relative mass and charge of a proton and where is it found

Answer 7

mass= 1
charge= +1
position= nucleus

Question 8

what is the relative mass and charge of a neutron and where is it found

Answer 8

mass= 1
charge= 0
position= nucleus

Question 9

what is the relative mass and charge of an electron and where is it found

Answer 9

mass= 1/1840
charge= -1
position= orbital

Question 10

define ions

Answer 10

atoms that have gained or lost electrons and are represented with a charge (positive/negative)

Question 11

what does a mass spectrometer do

Answer 11

measures the abundance of different isotopes

Question 12

what are the five main stages of mass spectrometry

Answer 12

vaporisation
1) ionisation
2) acceleration
3) deflection
4) detection

Question 13

what happens during ionisation in mass spectrometry

Answer 13

sample is vaporised, seperating the atoms or molecules. a stream of high energy electrons is fired at the sample, so the energy from these electrons strips electrons off atoms or molecules forming positive ions.

Question 14

what happens during acceleration in mass spectrometry

Answer 14

the positive ions pass through an electric field which accelerates them into the instrument

Question 15

what happens during deflection in mass spectrometry

Answer 15

the ions pass through a magnetic field and are deflected according to their mass and their charge

Question 16

whats happens during detection in mass spectrometry

Answer 16

an ion detector at the end of the tube responds to ions of a particular mass/charge ratio and mass spectrum is produced

the relative abundance of each ion is recorded as a peak on the spectrum

Question 17

what is the first ionisation energy

Answer 17

the energy required to remove one mole of electrons from each atom in 1 mole of gaseous atoms to form 1 mole of gaseous 1+ ions

Question 18

what is an orbital

Answer 18

a region within an atom that can hold up to 2 electrons of opposite spins

Question 19

what is a sub shell

Answer 19

a group of electrons in the same type of orbital within a shell (s, p, d or f)

Question 20

what is periodicity

Answer 20

a regularly repeating pattern of physical, atomic and chemical properties within a period (with increasing atomic number)

Question 21

what three factors affect 1st ionisation energy

Answer 21

the number of protons (nuclear charge)
the shielding
the atomic/ionic radius

Question 22

does ionisation energy increase or decrease across a period

Answer 22

increases as:
-nuclear charge increases
-shielding stays roughly the same
-atomic radius decreases slightly

Question 23

does ionisation energy increase or decrease down a group

Answer 23

decreases as:
-nuclear charge increases (outweighed)
-atomic radius increases
-shielding increases

Question 24

how do flame tests work chemically

Answer 24

electrons in lower energy levels will gain energy and temporarily be excited into higher energy levels. when the electrons return to a lower energy state, discrete energies are emitted

Question 25

what shape is an S orbital

Answer 25

spherical

Question 26

what shape is a P orbital

Answer 26

dumbell

Question 27

what order are the subshells filled in an atom

Answer 27

1s 2s 2p 3s 3p 4s 3d 4p 4d

Question 28

when do you not fill the 4s subshell before the 3d subshell

Answer 28

with Cr (chromium) and Cu (copper)

Question 29

in a period why does ionisation energy decrease from Be (beryllium) and B (boron)

Answer 29

2p electron is in a higher energy subshell than the 2s and so it is easier to remove the outer electron from B than Be

Question 30

in a period why does ionisation energy decrease between N (nitrogen) and O (oxygen)

Answer 30

two electrons are paired in the 2p subshell of oxygen, all of the 2p electrons are unpaired in nitrogen. there is greater repulsion with the paired electrons in oxygen so it is easier to remove

Question 31

what is the equation for Ar on a mass spec

Answer 31

m/z x abundance divided by total abundance

Question 32

what is the equation for Ar on a mass spec

Answer 32

m/z x abundance divided by total abundance

Question 33

what does atomic emission spectra provide evidence for

Answer 33

quantum shells