Save My Rxams Atomic Dtructure

Question 1

Atom structure

Answer 1

mostly made up of empty space around a very small, dense nucleus that contains protons and neutrons

Question 2

Nucleus charge

Answer 2

overall positive charge
The protons have a positive charge and the neutrons have a neutral charge

Question 3

Where electrons are found

Answer 3

Negatively charged electrons are found in orbitals in the empty space around the nucleus

Question 4

Proton mass

Answer 4

1

Question 5

Neutron mass

Answer 5

1

Question 6

Electron mass

Answer 6

1/1836

Question 7

Proton relative charge

Answer 7

+1

Question 8

Neutron relative charge

Answer 8

0

Question 9

Electron charge

Answer 9

-1

Question 10

Atomic number

Answer 10

is the number of protons in the nucleus of an atom and has symbol Z

equal to the number of electrons present

Question 11

mass number

Answer 11

is the total number of protons and neutrons in the nucleus of an atom and has symbol A

Question 12

number of neutrons can be calculated by:

Answer 12

mass number - atomic number

Question 13

what holds an atom together

Answer 13

electrostatic attraction between the positive nucleus and negatively charged electrons orbiting

Question 14

Atom charge

Answer 14

neutral and has no overall charge

Question 15

all atoms and ions of the same element have

Answer 15

the same number of protons
Diff neutron

Question 16

Isotopes

Answer 16

atoms of the same element that contain the same number of protons and electrons but a different number of neutrons

same chemical properties but different physical properties

Question 17

Chemical properties of isotope

Answer 17

display the same chemical characteristics
This is because they have the same number of electrons in their outer shells

Question 18

Physical properties of an isotope

Answer 18

difference between isotopes is the number of neutrons

isotopes have different physical properties such as small differences in their mass and density

Question 19

What Tof is used for

Answer 19

accurate determination of the relative atomic mass of an element, based on the abundance and mass of each of its isotopes

Question 20

4 key stages in time of flight mass spectrometry:

Answer 20

Ionisation
Acceleration
Ion drift
Detection

Question 21

1: Ionisation

Answer 21

Electron Impact (or electron ionisation)
Electrospray Ionisation

Question 22

Electron Impact Ionisation

Answer 22

substances which have a lower molecular mass

vaporised and then bombarded with high energy electrons

a hot wire filament which emits electrons as a current runs through it

electron is knocked off each particle, forming a 1+ ion

Question 23

Electrospray Ionisation

Answer 23

dissolved in a volatile solvent
The solvent is injected into the mass spectrometer using a hypodermic needle
This produces a fine mist or aerosol
The needle is attached to a high voltage power supply, so as the sample is injected, the particles are ionised by gaining a proton from the solvent

Question 24

Equation for electro spray

Answer 24

X (g) + H+ → XH+ (g)

Question 25

Acceleration

Answer 25

accelerated using an electric field They are all accelerated to have the same kinetic energy Lighter ions will move faster and heavier ions will move slower

Question 26

Ion Drift

Answer 26

1+ ions will pass through a hole in the negatively charged plate and move into a flight tube

Question 27

Detection

Answer 27

the 1+ ions will hit a negatively charged 'detector' plate As they hit this electric plate, they gain an electron This gaining of an electron discharges the ion, and causes a current to be produced This size of the current is proportional to the abundance of those ions hitting the plate and gaining an electron The detector plate is connected to a computer, which produces the mass spectrum

Question 28

time of flight is proportional to

Answer 28

the square root of the mass of the ions, showing that the lighter the ion the faster it will pass through and the quicker it will hit the detector.

Question 29

electron configuration

Answer 29

The arrangement of electrons in an atom

Question 30

Principal quantum numbers

Answer 30

N used to number the energy levels or quantum shells The lower the principal quantum number, the closer the shell is to the nucleus

Question 31

n = 1 : up to

Answer 31

2 electrons

Question 32

n = 2 : up to

Answer 32

8 electrons

Question 33

n = 3 : up to

Answer 33

18 electrons

Question 34

n = 4 : up to

Answer 34

32 electrons

Question 35

Subshell letters

Answer 35

S P D F

Question 36

Orbitals

Answer 36

Subshells contain one or more atomic orbitals

Question 37

S orbital shape

Answer 37

spherical in shape The size of the s orbitals increases with increasing shell number

Question 38

p orbital shape

Answer 38

a dumbbell shape

Question 39

Ground state

Answer 39

most stable electronic configuration of an atom which has the lowest amount of energy This is achieved by filling the subshells of energy with the lowest energy first

Question 40

block elements Have their valence electron(s) in

Answer 40

an s orbital

Question 41

4s orbital is filled before

Answer 41

the 3d orbital

Question 42

Ionisation Energy

Answer 42

the amount of energy required to remove one mole of electrons from one mole of gaseous atoms of an element to form one mole of gaseous ions kilojoules per mole (kJ mol-1)

Question 43

first ionisation energy

Answer 43

the energy required to remove one mole of electrons from one mole of atoms of an element to form one mole of 1+ ions

Question 44

size of the first ionisation energy is affected by four factors:

Answer 44

Size of the nuclear charge Distance of outer electrons from the nucleus Shielding effect of inner electrons Spin-pair repulsion

Question 45

Ionisation energy across a period

Answer 45

Across a period the nuclear charge increases This causes the atomic radius of the atoms to decrease, as the outer shell is pulled closer to the nucleus, so the distance between the nucleus and the outer electrons decreases The shielding by inner shell electrons remain reasonably constant as electrons are being added to the same shell It becomes harder to remove an electron as you move across a period; more energy is needed

Question 46

Dips in the trend

Answer 46

between beryllium and boron as the fifth electron in boron is in the 2p subshell, which is further away from the nucleus than the 2s subshell of beryllium

Question 47

From one period to the next

Answer 47

There is increased distance between the nucleus and the outer electrons as you have added a new shell There is increased shielding by inner electrons because of the added shell These two factors outweigh the increased nuclear charge

Question 48

Ionisation energy down a group

Answer 48

The number of protons in the atom is increased, so the nuclear charge increases But, the atomic radius of the atoms increases as you are adding more shells of electrons, making the atoms bigger So, the distance between the nucleus and outer electron increases as you descend the group The shielding by inner shell electrons increases as there are more shells of electrons These factors outweigh the increased nuclear charge, meaning it becomes easier to remove the outer electron as you descend a group So, the ionisation energy decreases

Question 49

Successive ionisation energies of an element

Answer 49

increase Removing an electron from a positive ion is more difficult than from a neutral atom attractive forces increase due to decreasing shielding and an increase in the proton to electron ratio

Question 50

First electron easy to remove

Answer 50

easily removed from the atom due to the spin-pair repulsion of the electrons in the 4s orbital

Question 51

Second electron. Ore diffulcukt

Answer 51

more difficult to remove than the first electron as there is no spin-pair repulsion

Question 52

Successive ionisation data can be used to:

Answer 52

Predict or confirm the simple electronic configuration of elements Confirm the number of electrons in the outer shell of an element Deduce the Group an element belongs to in the Periodic Table