Atoms and Moles

Question 1

What is the mass of an electron?

Answer 1

1/1840

Question 2

What is an isotope?

Answer 2

An atom with the same number of protons but different number of neutrons

Question 3

What is the atomic number?

Answer 3

Number of protons

Question 4

Why do some atoms of the same element have different mass numbers?

Answer 4

If they have different number of neutrons

Question 5

What do ions have different numbers of?

Answer 5

Protons and Electrons

Question 6

What is the relationship between protons and electrons in a negative ion?

Answer 6

There are more electrons than protons

Question 7

What is the relationship between protons and electrons in a positive ion?

Answer 7

There are more protons than electrons

Question 8

What 2 things affects the chemical properties of an element?

Answer 8

Number and arrangement of electrons

Question 9

Why do isotopes not change the chemical properties of an element?

Answer 9

Isotopes have the same configuration of electrons so they’ve got the same chemical properties

Question 10

What 2 physical properties are different with isotopes compared to elements?

Answer 10

Different densities

Rates of diffusion

Question 11

Who came up with one of the currently accepted models of the atom?

Answer 11

Bohr

Question 12

What did some ancient Greeks believe matter was made of?

Answer 12

They believed matter was made from invisible particles

Question 13

What did John Dalton describe atoms as at the start of the 19th century?

Answer 13

Solid spheres (different types of sphere made up of the different elements)

Question 14

What did JJ Thomson conclude after his experiments in 1897?

Answer 14

That atoms weren’t solid and invisible

Question 15

What did Thomson call the ‘electrons’?

Answer 15

Corpuscles

Question 16

What was Thomson’s model called?

Answer 16

Plum Pudding Model

Question 17

What was the Plum Pudding model?

Answer 17

A positively charged sphere with negatively charged electrons embedded in it

Question 18

What experiment did Rutherford conduct?

Answer 18

The gold foil experiment

Question 19

What did Rutherford’s gold foil experiment involve?

Answer 19

Firing alpha particles (+ve charge) at an extremely thin sheet of gold

Question 20

What did Rutherford expect the result of his experiment to be (due to the Plum Pudding Model)?

Answer 20

That most of the alpha particles were to deflect slightly

Question 21

What did Rutherford’s gold foil experiment show?

Answer 21

That the plum pudding model was incorrect

Question 22

What was the name of the model that Rutherford came up with?

Answer 22

Nuclear Model

Question 23

What was the Nuclear Model?

Answer 23

An atom with a tiny, positively charged nucleus at the centre of it with a cloud of negative electrons

Question 24

Where was most of the mass concentrated in the Nuclear Model?

Answer 24

At the centre, so most of the atom is empty space

Question 25

What did Henry Moseley discover?

Answer 25

Charge of the nucleus increased from one element to another in units of one

Question 26

After Moseley's discovery, what did Rutherford find when further investigating the nucleus?

Answer 26

That it called positively charged particles that he called protons

Question 27

Who discovered the neutron?

Answer 27

James Chadwick

Question 28

What were the 4 principals of Bohr's model?

Answer 28

- Electrons only exist in fixed orbits (shells) and not anywhere in between - Each shell has a fixed energy - When an electron moves between shells EM radiation is emitted or absorbed - Because the energy of the shells is fixed, the radiation will have a fixed frequency

Question 29

What did the Bohr model explain about noble gases?

Answer 29

Why they were inert (chemically inactive)

Question 30

How did the Bohr Model explain why the noble gases are inert?

Answer 30

He said that atoms can only hold a fixed number of electrons in a shell, and that an element's reactivity is due to it's electrons. So, when a shell is full of electrons, it's stable and doesn't react

Question 31

What is the relative atomic mass?

Answer 31

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

Question 32

Why are some relative atomic masses not a whole number in the periodic table?

Answer 32

Because it is an average mass of all the isotopes

Question 33

What is the relative isotopic mass?

Answer 33

The weighted mean mass of an atom of an isotope compared to 1/12th the mass of an atom of carbon-12

Question 34

What are mass spectrometers?

Answer 34

Devices which are used to find out what samples are made up of by measuring the masses of their components

Question 35

What is the relative molecular mass?

Answer 35

The average mass of a molecule compared to the mass of an atom of carbon-12

Question 36

How do you find the Mr?

Answer 36

Add up the relative atomic mass values of all the atoms in the molecule

Question 37

What is the relative formula mass?

Answer 37

The average mass of a formula unit compared to 1/12th the mass of an atom of carbon-12

Question 38

How do you find the relative formula mass?

Answer 38

Add up the relative atomic masses of all the ions in the formula unit

Question 39

What is a mole?

Answer 39

The unit for an amount of a substance

Question 40

How many particles are there in 1 mole?

Answer 40

6.02x10^23

Question 41

What is the equation linking number of moles, mass and molar mass?

Answer 41

Moles=Mass/Molar Mass

Question 42

What is molar mass?

Answer 42

The mass of one mole of something

Question 43

What similarities are there between the molar mass and the relative formula mass?

Answer 43

They have the same numerical value, just for molar mass you put 'g mol^-1' (grams per mole)

Question 44

What equation links number of moles, number of particles you have and number of particles in a mole?

Answer 44

Moles=Number of particles you have/Number of particles in a mole

Question 45

What equation links number of moles, volume (dm^3)?

Answer 45

Number of moles = Volume (dm^3)/24

Question 46

What equation links number of moles, volume (cm^3)?

Answer 46

Number of moles = Volume (cm^3)/24000

Question 47

What is the ideal gas equation?

Answer 47

pV=nRT where p=pressure, V=volume (m^3), n=number of moles, T=temperature (K) and R=the gas constant (J K^-1mol^-1)

Question 48

What is the gas constant value?

Answer 48

8.314 J K^-1mol^-1

Question 49

What does the SI unit pf the gas constant mean?

Answer 49

Units of energy per temperature increment per mole

Question 50

What does 2kPa equal?

Answer 50

2000 Pa

Question 51

How do you convert from oC to K temperature?

Answer 51

You add 273

Question 52

What is the concentration of a solution?

Answer 52

How many moles (or grams) of something are dissolved per 1 dm^3 of solution

Question 53

Describe what a dilute solution is

Answer 53

A solution that has fewer moles per dm^3 than another

Question 54

Describe what a concentrated solution is

Answer 54

A solution that has more moles per dm^3 than another

Question 55

What equation links number of moles and concentration and volume (in cm^3)?

Answer 55

Number of moles=(Concentration x Volume)/1000

Question 56

What equation links number of moles and concentration and volume (in dm^3)?

Answer 56

Number of moles=Concentration x Volume