Atoms and Moles Flashcards

1
Q

What is the mass of an electron?

A

1/1840

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2
Q

What is an isotope?

A

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

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3
Q

What is the atomic number?

A

Number of protons

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4
Q

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

A

If they have different number of neutrons

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5
Q

What do ions have different numbers of?

A

Protons and Electrons

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6
Q

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

A

There are more electrons than protons

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7
Q

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

A

There are more protons than electrons

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8
Q

What 2 things affects the chemical properties of an element?

A

Number and arrangement of electrons

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9
Q

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

A

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

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10
Q

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

A

Different densities

Rates of diffusion

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11
Q

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

A

Bohr

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12
Q

What did some ancient Greeks believe matter was made of?

A

They believed matter was made from invisible particles

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13
Q

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

A

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

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14
Q

What did JJ Thomson conclude after his experiments in 1897?

A

That atoms weren’t solid and invisible

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15
Q

What did Thomson call the ‘electrons’?

A

Corpuscles

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16
Q

What was Thomson’s model called?

A

Plum Pudding Model

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17
Q

What was the Plum Pudding model?

A

A positively charged sphere with negatively charged electrons embedded in it

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18
Q

What experiment did Rutherford conduct?

A

The gold foil experiment

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19
Q

What did Rutherford’s gold foil experiment involve?

A

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

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20
Q

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

A

That most of the alpha particles were to deflect slightly

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21
Q

What did Rutherford’s gold foil experiment show?

A

That the plum pudding model was incorrect

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22
Q

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

A

Nuclear Model

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23
Q

What was the Nuclear Model?

A

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

24
Q

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

A

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

25
Q

What did Henry Moseley discover?

A

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

26
Q

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

A

That it called positively charged particles that he called protons

27
Q

Who discovered the neutron?

A

James Chadwick

28
Q

What were the 4 principals of Bohr’s model?

A
  • 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
29
Q

What did the Bohr model explain about noble gases?

A

Why they were inert (chemically inactive)

30
Q

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

A

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

31
Q

What is the relative atomic mass?

A

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

32
Q

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

A

Because it is an average mass of all the isotopes

33
Q

What is the relative isotopic mass?

A

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

34
Q

What are mass spectrometers?

A

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

35
Q

What is the relative molecular mass?

A

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

36
Q

How do you find the Mr?

A

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

37
Q

What is the relative formula mass?

A

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

38
Q

How do you find the relative formula mass?

A

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

39
Q

What is a mole?

A

The unit for an amount of a substance

40
Q

How many particles are there in 1 mole?

A

6.02x10^23

41
Q

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

A

Moles=Mass/Molar Mass

42
Q

What is molar mass?

A

The mass of one mole of something

43
Q

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

A

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

44
Q

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

A

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

45
Q

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

A

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

46
Q

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

A

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

47
Q

What is the ideal gas equation?

A

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)

48
Q

What is the gas constant value?

A

8.314 J K^-1mol^-1

49
Q

What does the SI unit pf the gas constant mean?

A

Units of energy per temperature increment per mole

50
Q

What does 2kPa equal?

A

2000 Pa

51
Q

How do you convert from oC to K temperature?

A

You add 273

52
Q

What is the concentration of a solution?

A

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

53
Q

Describe what a dilute solution is

A

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

54
Q

Describe what a concentrated solution is

A

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

55
Q

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

A

Number of moles=(Concentration x Volume)/1000

56
Q

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

A

Number of moles=Concentration x Volume