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OCR Chemistry a level > Module 2 : Atoms And Reactions > Flashcards

Module 2 : Atoms And Reactions Flashcards

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1
Q

What is the relative mass and relative charge of a proton?

Where is it located?

A

Relative mass = 1
Relative charge = +1
In the nucleus

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2
Q

What is the relative mass and the relative charge of a neutron?
Where is it located?

A

Relative mass = 1
Relative charge = 0
In the nucleus

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3
Q

What is the relative mass and the relative charge of an electron?
Where is it located?

A

Relative mass = 1/2000
Relative charge = -1
It is found in orbitals around the nucleus

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4
Q

What is the mass number of an element on the periodic table?

A

The total number of protons and neutrons in the nucleus of an atom/ isotope of that element

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5
Q

What is the atomic number of an element on the periodic table?

A

The number of protons in the nucleus - it identifies the element.
All atoms of the same element have the same number of protons

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6
Q

What is an isotope?

A

Atoms of the same element with the same number of protons but different numbers of neutrons

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7
Q

Why do isotopes have the same chemical properties?

A

The chemical properties of an element are caused by the charged particles in the atom. In isotopes the number of protons and the configuration of electrons are the same so they have that same chemical properties. The only thing that differs in isotopes is the number of neutrons and they are not charged.

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8
Q

What do the physical properties of an element depend on?

What does this tell you about isotopes?

A

The mass of the atom.

That isotopes have different physical properties.

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9
Q

What is the definition of relative atomic mass?

A

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

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10
Q

What is the definition of relative isotopic mass?

A

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

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11
Q

How do you calculate the relative atomic mass from isotopic abundances?

A

Step 1 : Multiply each relative isotopic mass by its % relative isotopic abundance, and add up the results

Step 2 : Divide by 100

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12
Q

How do you calculate the relative atomic mass from mass spectrometry graphs?

A

Step 1 : Multiply each relative isotopic mass by its % relative isotopic abundance, and add up the results

Step 2 : Divide by the sum of the isotopic abundances

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13
Q

What is the units for the ‘amount of substance’?

What is the symbol that represents this in formulas?

A 
Units = mole (mol)
Symbol = n
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14
Q

What is the definition of relative molecular mass?
What is its symbol?
When is this term used?
How is it calculated?

A

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

Mr

It is used for simple molecules.

It is calculated by adding together the relative atomic masses of each atom making up a molecule:
E.g
Mr of Cl2 = 35.5 + 35.5 = 71.0

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15
Q

What is the definition of relative formula mass?
When is this term used?
How is it calculated?

A

The weighted mean mass of a FORMULA UNIT compared with 1/12th of an atom of carbon-12

It is used for compounds with giant structures

It is calculated by adding together all of the relative atomic masses of each atom making up a formula unit.
E.g
CaBr2 = 40.1 + 79.9 +79.9 = 199.9

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16
Q

What is Avogadro constant?

A

The number of particles per moles

6.02 x 10^23

17
Q

What is molar mass?

What are the units for molar mass?

A

Mass per mole of a substance.

The units are: g mol ^-1

18
Q

What is molar gas volume?

What are the units for molar gas volume?

A

Gas volume per mole of a substance

The units are: dm^3 mol^-1

19
Q

What is the empirical formula?

How do you calculate it?

A

The simplest whole number ratio of atoms of each element in a compound.

Step 1 : divide the mass / percentage composition by the molar mass of the element/ compounds

Step 2 : divide the answers by the smallest answer - this will give you the ratio

Step 3 : the ratio is the number of atoms of that element present in the empirical formula

20
Q

What is the molecular formula?

How do you calculate it?

A

The actual number of atoms of each type of element in a molecule.

Step 1 : calculate the empirical mass - add together all of the relative atomic masses of the atoms in the empirical formula.

Step 2 : divide the molecular mass by the empirical mass (mm/em)

Step 3 : multiply the empirical formula by the answer

21
Q

What is the formula of the following ions?

  • nitrate
  • carbonate
  • sulfate
  • hydroxide
  • ammonium
  • zinc ion
  • silver ion
A
  • NO3^-
  • CO3^2-
  • SO4^2-
  • OH^-
  • NH4^+
  • Zn^2+
  • Ag^+
22
Q

What does anhydrous mean?

A

A substance that does NOT contains water molecule

23
Q

What does hydrated mean?

A

A crystalline substance that contains water molecules

24
Q

What does water of crystallisation mean?

A

Water molecules forming an essential part of a compounds crystal structure

25
Q

How do you calculate the molecules of water in a hydrated compound?

A

Step 1 ; calculate the mass of water lost (mass of hydrater salt minus mass of anhydrous salt)

Step 2 : calculate the number of moles of water lost (divide the mass of the water by the molar mass of water)

Step 3 : calculate the number of moles in the anhydrous salt (divide the mass of the anhydrous salt by the molar mass of the anhydrous salt)

Step 4 : work out the ratio of moles of anhydrous salt to moles of water (divide the moles of water with the moles of anhydrous salt)

26
Q

What are the equation triangles you need to know?

A

m
_____________
n | Mr

    V \_\_\_\_\_\_\_\_\_\_\_\_\_    n    | 24 dm^3

    n \_\_\_\_\_\_\_\_\_\_\_\_\_\_    c    |    V
27
Q

What is the ideal gas equation?

What are the units for each part of it?

A

Used when the a reaction happens not in room temperature and pressure

pV = nRT

p = pressure (Pa)
V = volume (m^3)
n = number of moles 
R = gas constant (8.134 JK^-1 mol^-1)
T = temperature (k)
28
Q

How do you calculate degrees Kelvin?

A

Degrees celcius + 273

29
Q

How do you calculate percentage yield?

A

Actual yield
_____________ X 100

Theoretical yield

30
Q

How do you calculate atom economy?

A

Molecular mass of desired product
_____________________________________ X 100

Sum of molecular masses of all products

31
Q

What is an acid?

A

A proton donor

They produce H+ ions in aqueous solutions

32
Q

What is a base?

A

A proton acceptor

They produce OH- ions in solutions

33
Q

Name and state the formula of the 4 common acids

A

HCL - hydrochloric acid
H2SO4 - sulfuric acid
HNO3 - nitric acid
CH3COOH - ethanoic acid

34
Q

Name and state the formula of the 3 common bases

A

NaOH - sodium hydroxide
KOH - potassium hydroxide
NH3 - ammonia

35
Q

What is a strong acid/base?

What is a weak acid/base?

A

A strong acid/base is one that can dissociates fully into its ions

A weak acid/base is one that can partially dissociate into its ions

36
Q

Acids and bases neutralise each other.

What is produced when you react an acid and an alkali?

A

A salt and water

OCR Chemistry a level (1 decks)

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