atomic structure test revision

Question 1

what are elements, how many are there, and what are they ordered on

Answer 1

• elements are the basic building blocks of all matter having one atom making that element up
• elements are ordered on the periodic table
• there are 112 different elements at this time but there are 118 to be know only elements 113, 115, 117 and 118 are unknown

Question 2

who first thought of atoms

Answer 2

Greek philosopher, Democritus in 400BC

Question 3

who is John Dalton and what did he prove/discover?

Answer 3

• In 1808, John Dalton described atoms as tiny balls of material. He said the atoms of a particular element are all identical
• He used small wooden balls to model atoms and showed how they could combine to produce a compound

Question 4

who is JJ Thomson and what did he prove/discover?

Answer 4

• In 1897, Thomson discovered ‘cathode rays’. On closer examination, these ‘rays; were in fact tiny, negatively charged particles being emitted from atoms, otherwise known as the electron. This then proved that there were smaller particles then atoms.
• His model stated that since there were negatively charged particles in the atom that there had to be a positive particle to cancel it out. So, he came up with the plum pudding model and said that atoms were lumps of positively charged material with the negatively charged electrons scattered through the atom

Question 5

Who is Earnest Rutherford and what did he prove/discover?

Answer 5

• In 1911, Earnest Rutherford carried out an experiment that proved that atoms were not solid lumps of material but were actually mostly empty space with a very small solid center called the nucleus
• He came up with a new model which had a solid, positively charged center and the negative electrons in ‘orbits’ around it. It was basically what is accepted as today’s model but it’s one flaw was that it proposed that the orbiting electrons would eventually lose energy and spiral towards the nucleus

Question 6

Who is Neils Bohr and what did he prove/discover?

Answer 6

• In 1913, Bohr experimented with the energy being emitted and absorbed in atoms and came up with the theory that electrons are inhabited within fixed shells or orbits.
• Only electrons with a certain amount of energy could move from one level to another by gaining or losing energy
• His model included a central nucleus that was positive and the electrons having fixed shells around it

Question 7

Who is James Chadwick and what did he prove/discover?

Answer 7

In 1932, Chadwick identified the neutron as he noticed an unusual radiation that had been observed in some experiments was actually a neutral sub-atomic particle

Question 8

what is the atomic number of an element?

Answer 8

the number of protons it contains

Question 9

what is the atomic mass of an element?

Answer 9

the number of protons and neutrons it contains

Question 10

what is the nuclide representation?

Answer 10

A
E
Z

A = mass number
Z = atomic number
E = element symbol

Question 11

what is an ion?

Answer 11

• Ions are charged elements that have gained or lost electrons
• if the element is negative the atoms has gained electrons and if it is positive then it has lost an electron

Question 12

what is the electron configuration?

Answer 12

• the number of each electron on each shell

- 2,8,18…..

Question 13

what is the max number of electrons for each shell

Answer 13

1 - 2
2 - 8
3 - 18
4 - 32
5- 50

Question 14

how does the electron arrangement relate to its position of the periodic table?

Answer 14

number of shells = period number

number of electrons = group number

Question 15

what are subshells

Answer 15

subshells are the area in which electrons move within a shell (sub energy levels within a shel;

Question 16

what are orbitals

Answer 16

orbitals are regions where up to 2 electrons exist

Question 17

what are the subshells symbols and how many electrons fit into them?

Answer 17

s subshell - 2 electrons

p subshell - 6 electrons

d subshell - 10 electrons

f subshell - 14 electrons

Question 18

what is the order of filling

Answer 18

the filling of subshells according to the energy levels of the shell (lowest level fills first)

1s2, 2s2, 2p6, 3s2, 4s2, 3d10, 4p6, 5s2, 4d10 ……

Question 19

what are the periodic trends

Answer 19

• atomic radius
• electronegativity
• chemical reactivity
• ionisation energy
• metallic character

Question 20

how can the periodic table be broken up into blocks

Answer 20

it can be broken up into blocks based on the last subshell being filled. the ‘s’ block has the last subshell being filled and only has 2 elements per period

Question 21

how does the atomic radius work

Answer 21

• when you go down a group on the periodic table the radius gets bigger because there are more shells
• Across a period the radius gets smaller because as more electrons are added to the same shell going across the force of attraction between the nucleus and valence shell increases causing the valance shell to go closer to the center

Question 22

what is metallic character

Answer 22

• the metallic nature of an element depends on the valence electrons
• metals like to lose electron and as it become easier to lose electrons metallic character increases
• metallic character increases going down a period but isn’t as clear going across a period as the metallic character decreases because the radius of an atom decreases meaning electrons are harder to lose

Question 23

what is electronegativity

Answer 23

• this property is the ability of an atom to hold onto its electrons
• if an atom has less than 4 electrons in the valence shell then it will prefer ti gain electrons and not lose, hence it become electronegative
• electronegativity decreases going down a group and increases going across a period

Question 24

what is chemical reactivity

Answer 24

• chemical reactivity means that when an element is more reactive if its valence shell is not full
• chemical reactivity will increase going down a group because it is easier to lose electrons going down because there is more shells and less force attraction

Question 25

what is ionisation energy

Answer 25

ionisation energy is the amount of energy required to remove an electron from an atom
- the FIRST ionisation energy is the amount of energy it requires to remove the FIRST electron from an atom

Question 26

what are isotopes

Answer 26

isotopes are atoms that are apart of the same element with the same atomic number but with a different mass numbers

Question 27

what is the relative isotopic mass

Answer 27

relative isotopic mass is the average mass of a particular isotope of an element relative to the mass of the carbon 12 isotope taken as 12 units exactly

Question 28

what is the relative atomic mass

Answer 28

relative atomic mass is the weighted average mass of an atom, taking the natural abundances of all its isotopes into account, relative to the mass of the carbon 12 scale

Question 29

how do you calculate the RAM

Answer 29

                                       100

Question 30

find the RAM of the two boron natural isotopes

80% of boron is B11 (6 neutrons)
20% of boron is B10 (5 neutrons)

Answer 30

         100 = 10.8

Question 31

what is the mass spectrometer

Answer 31

the mass spectrometer is an instrument that can be used to determine the mass and abundance of isotopes of an element

Question 32

how does the mass spectrometer work

Answer 32

it works on the principle that charged particles can be affected by a magnetic field. the first step is ionisation which forms the positive ions. these ions are then accelerated and then deflected by a large magnetic field. The lighter ions get deflected more than the heavier ones and more highly charged ions get deflected than singly charged ions. then, an electric beam detects the particles as they pass, and a mass spectrum is produced.

Question 33

what is ionisation in the mass spectrometer

Answer 33

ionisation is where the atoms are ionised by the bombardment with high-energy electrons which makes them positively charge

Question 34

what is acceleration

Answer 34

acceleration is when the positively charged species are accelerated by attraction towards negatively charged plates

Question 35

what is deflection

Answer 35

deflection is when the ions are deflected by a magnetic field. lighter ions get deflected more than the heavier ones

Question 36

what is detection

Answer 36

detection is when the particles are detected as a small current because they are charged, counting the number if particles detected and then plots their mass to charge ratio

Question 37

what is Relative Molecular Mass / Relative Formula Mass

Answer 37

RMM/RFM is the weighted sum of the individual relative atomic masses of its atoms

Question 38

how is RMM/RFM found

Answer 38

the mass of a molecule or an ionic compound is found by adding all the separate contributing masses of each atom

Question 39

Find the RMM of NaCl

Answer 39

= mass (Na) + mass (Cl)
= 23.0 + 35.5
= 58.5

Question 40

how do you find the percentage composition

Answer 40

% = mass (element 1)
—————————- x 100
mass (full molecule)

Question 41

find the percentage of Na by mass in NaCl

then, find the percentage of Cl by mass

Answer 41

% (Na) =
mass (Na)
————— x 100
mass (NaCl)

= 23.0/58.5 x 100
= 39.3%

% (Cl)
100-39.3 = 60.7%
OR
35.5/58.5 x 100 = 60.7%