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CHEM Flashcards

(101 cards)

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1
Q

What are the three states of matter?

A

Solid, liquid, and gas.

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2
Q

How are particles arranged in a solid?

A

Particles are tightly packed in a regular arrangement, vibrating in fixed positions.

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3
Q

How are particles arranged in a liquid?

A

Particles are close together but can move past each other, with a less regular arrangement.

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4
Q

How are particles arranged in a gas?

A

Particles are far apart, moving randomly with high energy and no fixed arrangement.

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5
Q

What are the interconversions between states of matter?

A

Melting, freezing, boiling, condensing, sublimation, and deposition.

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6
Q

How is melting achieved?

A

By heating a solid to its melting point, increasing particle energy.

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7
Q

How is condensation achieved?

A

By cooling a gas below its boiling point, decreasing particle energy.

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8
Q

What experiment explains diffusion of gases?

A

Gases diffuse from high to low concentration, observed by spreading of perfume in air.

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9
Q

What is a solvent?

A

The substance in which a solute dissolves.

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10
Q

What is a solute?

A

The substance dissolved in a solvent.

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11
Q

What is a solution?

A

A homogeneous mixture of solute and solvent.

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12
Q

What is a saturated solution?

A

A solution that contains the maximum amount of solute dissolved at a given temperature.

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13
Q

How do you classify a substance as an element, compound, or mixture?

A

Element: made of one type of atom; compound: made of two or more elements chemically bonded; mixture: physically combined substances.

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14
Q

Do pure substances have fixed melting and boiling points?

A

Yes. Mixtures melt or boil over a range of temperatures.

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15
Q

Name techniques to separate mixtures.

A
  • Simple distillation
  • Fractional distillation
  • Filtration
  • Crystallisation
  • Paper chromatography
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16
Q

How does a chromatogram show the composition of a mixture?

A

By displaying different spots or bands representing components; Rf values help identify them.

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17
Q

How do you calculate Rf values?

A

Rf = distance moved by substance / distance moved by solvent front.

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18
Q

What is an atom?

A

The smallest unit of an element, consisting of protons, neutrons, and electrons.

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19
Q

What is a molecule?

A

Two or more atoms bonded together.

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20
Q

Where are sub-atomic particles located?

A

Protons and neutrons in the nucleus; electrons in shells surrounding the nucleus.

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21
Q

What are atomic number and mass number?

A
  • Atomic number: number of protons
  • Mass number: protons + neutrons
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22
Q

What are isotopes?

A

Atoms with the same atomic number but different neutron numbers.

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23
Q

How is relative atomic mass (Ar) calculated?

A

Using isotopic abundances: Ar = (sum of isotopic mass × abundance) / 100.

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24
Q

How are elements arranged in the periodic table?

A

In order of increasing atomic number, in groups (columns) and periods (rows).

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25
How do you deduce electronic configuration from the periodic table?
By the group number: main group elements have electrons in s and p shells according to their group.
26
How are metals and non-metals classified?
Metals are to the left and middle; non-metals to the right.
27
Why do elements in the same group have similar properties?
Because they have the same number of electrons in their outer shell.
28
Why are noble gases unreactive?
Because their outer shells are full.
29
How do you write a word and balanced symbol equation?
Word: describing substances; balanced: ensures equal atoms of each element on both sides (with state symbols).
30
How do you calculate relative formula mass (Mr)?
Sum of Ar of all atoms in the formula.
31
What is a mole?
The unit for amount of substance, containing 6.02 × 10²³ particles.
32
How do you find reacting masses?
Using balanced equations, molar ratios, and Ar/Mr.
33
How is percentage yield calculated?
(Actual yield / Theoretical yield) × 100%.
34
What are empirical and molecular formulas?
* Empirical: simplest whole-number ratio * Molecular: actual number of atoms
35
How to determine the formula of a metal oxide?
By combustion or reduction, measuring masses before and after.
36
How are ions formed?
By electron loss (metals) or gain (non-metals).
37
What are common positive ions (cations)?
* Na⁺ * K⁺ * Ca²⁺ * Ag⁺ * Cu²⁺ * Fe²⁺ * Fe³⁺ * Pb²⁺ * Zn²⁺ * H⁺
38
What are common negative ions (anions)?
* OH⁻ * NO₃⁻ * SO₄²⁻ * CO₃²⁻ * Cl⁻ * Br⁻ * I⁻ * NH₄⁺
39
How do you write formulae for ionic compounds?
Combine ions in ratios that balance total charge to zero.
40
Why do ionic compounds have high melting points?
Due to strong electrostatic forces in giant ionic lattices.
41
Do ionic compounds conduct electricity?
Yes, when molten or in solution, but not as solids.
42
How is a covalent bond formed?
By sharing a pair of electrons between atoms.
43
What is a dot-and-cross diagram?
A visual representation showing shared electrons, with dots and crosses for different atoms.
44
How do we represent molecules like H₂, O₂, N₂, HCl, H₂O, CO₂?
Using structural or displayed formulas showing bonds and lone pairs.
45
Why do substances with simple molecular structures have low melting and boiling points?
Because intermolecular forces are weak.
46
How does molecular mass affect melting and boiling points?
Higher molecular mass generally means higher melting and boiling points.
47
Why are giant covalent structures solid with high melting points?
Due to strong covalent bonds throughout the structure.
48
How do structures of diamond, graphite, and fullerenes differ?
* Diamond: 3D covalent network (hard, high melting point) * Graphite: layers of hexagonal rings (soft, conducts electricity) * Fullerenes: molecules with curved surfaces.
49
Do covalent compounds conduct electricity?
Usually no, except some with delocalized electrons (like graphite).
50
How do alkali metals react with water?
They produce hydroxides and hydrogen gas, becoming more reactive down the group.
51
How do reactions with air/water show trends in alkali metals?
Reactivity increases down the group.
52
What are the physical states and colours of chlorine, bromine, iodine?
* Cl₂: green gas * Br₂: red-brown liquid * I₂: grey solid/violet vapour
53
How does reactivity change in Group 7 (Halogens)?
Reactivity decreases down the group.
54
What are the main gases in dry air?
* Nitrogen (78%) * Oxygen (21%) * Argon (0.9%) * Carbon dioxide (0.04%)
55
How to determine oxygen percentage?
By observing reactions of metals or non-metals with air.
56
What are the products of combustion?
* Metals: metal oxides * Hydrocarbons: CO₂ and H₂O * Sulfur: SO₂
57
How are metals arranged in the reactivity series?
Based on their reactivity with water and acids.
58
What is rusting and how to prevent it?
Iron reacts with oxygen and water; prevented by barrier methods, galvanizing, or sacrificial protection.
59
What is oxidation and reduction?
* Oxidation: loss of electrons * Reduction: gain of electrons
60
How to identify acids and alkalis with indicators?
* Litmus turns red in acid, blue in alkali * Phenolphthalein turns pink in alkali * Methyl orange: red in acid, yellow in alkali.
61
What does pH measure?
Acidity or alkalinity; 0–3 (strong acid), 4–6 (weak acid), 7 (neutral), 8–10 (weak alkali), 11–14 (strong alkali).
62
How do acids and alkalis neutralize?
Acids donate H⁺ ions; alkalis donate OH⁻ ions, forming water and salts.
63
What are rules for solubility?
* Sodium, potassium, ammonium salts are soluble * Nitrates are soluble * Silver and lead chlorides are insoluble * Barium, calcium, lead sulfates are insoluble * Carbonates insoluble except for Na, K, NH₄ * Hydroxides insoluble except for Na, K, Ca.
64
How are salts prepared?
By reacting acids with metals, metal oxides, hydroxides, or carbonates; filter, wash, and dry.
65
How to test for hydrogen?
Place a burning splint; squeaky pop.
66
How to test for oxygen?
Relights a glowing splint.
67
How to test for carbon dioxide?
Bubble through limewater; turns cloudy.
68
How to test for ammonia?
Turns damp red litmus paper blue.
69
How to test for chlorine?
Turns damp litmus paper white (bleaches).
70
What are the flame test colours for Li⁺, Na⁺, K⁺, Ca²⁺, Cu²⁺?
* Li⁺: red * Na⁺: yellow * K⁺: lilac * Ca²⁺: orange-red * Cu²⁺: blue-green.
71
How to identify metal cations with NaOH?
Form characteristic precipitates: Cu(OH)₂ (blue), Fe(OH)₂ (green), Fe(OH)₃ (brown).
72
How to identify halide ions?
Acidified AgNO₃: Cl⁻ (white precipitate), Br⁻ (cream), I⁻ (yellow).
73
How to test for sulfate ions?
Acidified BaCl₂: forms a white precipitate.
74
How to test for carbonate ions?
Add HCl; gas evolved turns limewater cloudy.
75
How to test for water?
Anhydrous CuSO₄ turns blue when hydrated.
76
What is an exothermic reaction?
A reaction that releases heat energy.
77
What is an endothermic reaction?
A reaction that absorbs heat energy.
78
How is calorimetry used?
To measure temperature change during reactions like combustion or neutralization.
79
How is heat energy change calculated?
Q = mcΔT (mass × specific heat capacity × temperature change).
80
How to calculate molar enthalpy change (ΔH)?
ΔH = Q / mol of substance.
81
What factors affect reaction rates?
* Surface area * Concentration * Temperature * Catalysts.
82
How does increasing surface area affect rate?
It increases the rate.
83
How do catalysts work?
They provide an alternative pathway with lower activation energy.
84
What indicates a reversible reaction?
The use of the ⇌ symbol.
85
What is a hydrocarbon?
A compound made of hydrogen and carbon only.
86
What is a homologous series?
A series of compounds with similar structures and properties, differing by CH₂.
87
What is a functional group?
A specific group of atoms responsible for the characteristic reactions.
88
What is isomerism?
Compounds with the same molecular formula but different structures.
89
How are compounds named?
Using IUPAC rules for compounds up to 6 carbons.
90
What is crude oil?
A mixture of hydrocarbons.
91
How is crude oil separated?
By fractional distillation.
92
What are the main fractions and their uses?
* Refinery gases * Gasoline * Kerosene * Diesel * Fuel oil * Bitumen.
93
What is the general formula for alkanes?
CₙH₂ₙ₊₂.
94
Are alkanes saturated?
Yes, they contain only single bonds.
95
What is the functional group in alkenes?
The carbon-carbon double bond (>C=C<).
96
Are alkenes saturated?
No, they are unsaturated.
97
What is the general formula for alkenes?
CₙH₂ₙ.
98
How do alkenes react with bromine?
They add bromine across the double bond to form dibromoalkanes.
99
How can bromine water distinguish alkanes and alkenes?
Alkenes decolorize bromine water; alkanes do not.
100
What is an addition polymer?
A polymer formed by joining many monomers through addition reactions.
101
What are disposal problems of addition polymers?
They are inert, do not biodegrade, and produce toxic gases when burned.

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