[ chem module 2 key definitions ] Flashcards

1
Q

What is the atomic number?

A

The number of protons an element has.

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2
Q

What is an isotope of an element?

A

An isotope of an element will have the same number of protons and electrons but a different number of neutrons.

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3
Q

What is an ion?

A

An ion is a charged atom which either lost or gained electrons.

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4
Q

What is the difference between a cation and anion?

A

Cation is a positive ion which lost electrons.
Anion is a negative ion which gained electrons.

[Try remember anion as an onion which is bad boo hoo therefore negative]

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5
Q

What is the relative isotopic mass?

A

The mass of an isotope relative to 1/12th the mass of a carbon-12 atom.

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6
Q

What is the definition of relative atomic mass?

A

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

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7
Q

How do you calculate the relative atomic mass?

A

Contribution from isotope x percentage / 100

For example, (75.78x35) + (24.22x37) / 100

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8
Q

What is the formulae for an ammonium ion?

A

NH4+

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9
Q

What is the formulae for a hydroxide ion?

A

OH-

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10
Q

What is the formulae for a nitrate ion?

A

NO3-

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11
Q

What is the formulae for a carbonate ion?

A

CO3 2-

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12
Q

What is the formulae for a sulfate ion?

A

SO4 2-

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13
Q

Example question: What is the formulae for zinc chloride?

A

ZnCl2

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14
Q

Example question: What is the formulae for aluminium sulfate?

A

Al2(SO4)3

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15
Q

What is the avogadro constant?

A

The number of particles in each mole of carbon-12 atom.

6.02x 10^23

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16
Q

What are the three mol equations?

A

Mol: Mass/Mr
Mol: Conc x Vol (dm3)
Mol: Vol/24 (for gases)

17
Q

What is the molecular formulae?

A

The number of atoms of each element in a molecule.

18
Q

What is the empirical formulae?

A

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

19
Q

Example question: What is the empirical formulae for C6H12O6

A

CH2O

20
Q

How do you calculate empirical formulae?

A

1) Do mass/mol or percentage/mr

2) Find the simplest whole number ratio and divide the smallest whole number

21
Q

Example question: Chemical analysis of a compound gave composition by mass C: 40% H: 6.67% O: 53.33%

A

C6H12O6

[Ask me if u don’t understand why hehe]

22
Q

What are the water of crystallisation?

A

The water molecules that are part of a crystalline structure.

23
Q

What does it mean when a Crystal is hydrated?

A

It contains water molecules.

24
Q

What does it mean when a crystal is anhydrous?

A

Water molecules are absent.

25
Q

Why do you assume during water of crystallisation experiments?

A

+All of the water has been lost

+There is no further decomposition

26
Q

What is the ideal gas equation? What does each letter represent and what unit is used?

A

pV= nRT

p: pressure (Pa)
V: volume (m3)
n: mol
R: ideal gas constant (8.31 jmol-1K-1)
T: temperature (K which is degrees +273)
27
Q

What is the equation for percentage yield?

A

Percentage yield= Actual yield/Theoretical yield x 100

28
Q

What is atom economy?

A

The sum of molar masses of desired products/ The molar masses of all products x 100

29
Q

What is the difference between a strong and weak acid?

A

A strong acid like HCL will completely dissociate (release all H+ ions) wheres a weak acid like CH3COOH will only partially dissociate (release some H+ ions)

30
Q

What is an alakli?

A

A base that will dissolve in an aqueous solution and release OH- ions

31
Q

What is a salt?

A

A chemical compound formed when the H+ atom is replaced by a metal. For example sodium chloride (NaCl)

32
Q

What is an acid?

A

A substance when dissolved in H2O will release hydrogen ions (H+)

33
Q

What is formed when an acid reacts with a metal oxide/hydroxide?

A

Acid + Metal Oxide/Hydroxide -> Salt + Water

34
Q

Example Question: What is formed when Copper oxide reacts with sulfuric acid? Write both the word and symbol equation with state symbols.

A

Word: Copper oxide + Sulfuric acid -> Copper Sulphate and Water
Symbol: CuO (s) + H2SO4 (aq) -> CuSO4 (aq) + H2O (l)

35
Q

What is formed when acids react with carbonates?

A

Acid + Carbonate -> Salt + Water + Carbon Dioxide

36
Q

What is an oxidation number?

A

The number of electrons involved in bonding.

37
Q

What is a standard solution in titrations?

A

A solution with a known concentration.