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Chemistry > Key Concepts In Chemistry > Flashcards

Key Concepts In Chemistry Flashcards

1
Q

What does oxidising mean

A

Allows other materials to burn more fiercely

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2
Q

What does harmful mean

A

Can cause irritation, reddening or blistering of the skin

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3
Q

What does environmental hazard mean

A

Harmful to organisms and to the environment

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4
Q

What does highly flammable mean

A

Catches fire easily

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5
Q

What does toxic mean

A

Can cause death

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6
Q

What does corrosive mean

A

Destroys materials

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7
Q

What is a hazard

A

Anything that has the potential to cause harm or damage

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8
Q

What is a risk

A

The probability that someone or something being harmed if they are exposed to the hazard

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9
Q

How has the theory of atomic structure changed over time

A

Early 19th century - Dalton - atoms as solid spheres
1897 - Thomson - plum pudding
1909 - Rutherford - nuclear atom
Later - Bohr - refined model

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10
Q

What is mass number

A

No. of protons + neutrons

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11
Q

What is atomic number

A

No. of protons and electrons

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12
Q

How are isotopes different

A

They have a different no. of neutrons

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13
Q

What is relative atomic mass

A

The average mass of one atom of the element compared to 1/12th the mass of one atom of C-12

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14
Q

How to work out isotope abundances

A

Isotopic mass x isotope abundance/ isotopes abundances added

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15
Q

Who made the first periodic table

A

Dmitri Mendeleev in 1869

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16
Q

What are 3 differences between his periodic table and the current one

A
  • Mendeleev left gaps
  • Mendeleev arranged in order of atomic mass
  • Didn’t include Noble gases
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17
Q

What is the maximum no. of electrons in each shell

A

1 - 2
2 - 8
3 - 8

18
Q

What is an ion

A

A charge particle

19
Q

When are ionic bonds formed

A

When a metal and non-metal react

20
Q

Properties of ionic compounds

A
  • high melting and boiling point as they are held together by strong electrostatic forces of attraction
  • don’t conduct electricity as a a solid
  • conduct electricity when liquid or dissolved in water
21
Q

2D representations

A

-Show what and how the atoms are connected in a substance
- Doesn’t show the shape of the substance
- Doesn’t show the size of the atoms

22
Q

Dot and cross

A
  • How the compound is formed
  • Don’t show the arrangement
23
Q

3D models

A

-Show arrangement of ions
- Only show the outer layer

24
Q

Ball and Stick

A
  • Good for visualisation
  • Leave big gaps between atoms
  • Don’t show correct scale for atoms
25
Q

Properties of simple molecular substances

A
  • Low melting and boiling points as there are weak intermolecular forces
  • Don’t conduct electricity
26
Q

Properties of giant covalent substances

A
  • Strong covalent bonds
  • High melting and boiling points
  • Generally don’t conduct electricity apart from graphite and graphene
27
Q

Diamond

A
  • Each Carbon forms 4 covalent bonds
  • High melting point
  • Lattice structure
  • Doesn’t conduct electricity as there are no free electrons
28
Q

Graphite

A
  • Each Carbon only forms 3 bonds
  • Sheets arranged in hexagons
  • Layers held together weakly
  • Soft and slippery
  • High melting point
  • Conducts electricity as one delocalised electron
29
Q

What is graphene

A

One layer of graphite

30
Q

What is a fullerene

A

Molecules of carbon

31
Q

Uses of fullerenes

A

Drug delivery around the body
Lubricants
Energy storage

32
Q

Properties of metals

A

high boiling points due to strong electrostatic forces of attraction
usually shiny solids at room temperature
malleable as layers can slide over each other
good conductors of electricity and heat

33
Q

What is the empirical formula

A

The simplest ratio of atoms

34
Q

How much does one mole of a substance weigh

A

Grams of the Mr of that substance

35
Q

What is avogadro’s number

A

6.023 x 10^23

36
Q

Formula for no. of moles

A

Mass in g/ Mr

37
Q

Formula for concentration (dm^3)

A

mass / volume
ALSO
no. / volume

38
Q

Formula for no. of moles in a gas

A

volume / 24 (dm^3)

39
Q

How to work out the empirical formula

A

Work out no. of moles
Divide by smallest no. to form ratio

40
Q

What is a limiting reactant

A

A reactant that stops the reaction when all of it is used up
The amount of product formed is proportional to the amount of reactant

Chemistry (9 decks)

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