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Chemistry > Unit 1 - Chemical Changes > Flashcards

Unit 1 - Chemical Changes Flashcards

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1
Q

What is an element?

A

A substance made up of entirely one type of atom

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2
Q

Each atom is made up of smaller particles called sub-atomic particles. What are the 3 sub-atomic particles called?

A

Proton
Neutron
Electron

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3
Q

What is the charge of each particle, where is each one located and what is their relative mass?

A

Proton - Positive charge, Located in the nucleus, a.m.u = 1
Neutron - Neutral charge, in the nucleus, a.m.u = 1
Electron - Negative charge, orbits the nucleus, a.m.u = 0

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4
Q

What is the atomic number of an element also equal to?

A

The number of protons found in the atom’s nucleus

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5
Q

In atoms, what is the number of protons also equal to?

A

The number of electrons

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6
Q

How are electrons arranged?

A

Electrons orbit the nucleus in energy levels. The electron arrangement displays the number and location of the electrons within these energy levels

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7
Q

What can the number of electrons in the outer energy level indicate?

A

The reactivity of the element

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8
Q

How many electrons can be stored in each energy level (for levels 1-3)?

A

1st energy level - holds up to 2 electrons
2nd - Up to 8 electrons
3rd - Up to 8 electrons

Note; the lowest energy levels are filled up first by the electrons

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9
Q

What is important when drawing dot diagrams when there are less than 5 electrons?

A

When drawing dot diagrams, electrons are placed individually around the electron shell. Then you start pairing them up once there are 5 electrons or more

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10
Q

What is the mass number of an atom equal to?

A

The number of protons + the number of neutrons. This allows you to calculate the number of neutrons if unknown. To do so, use the atomic number (which is the same as the number of protons) and take it away from the mass number which will tell you the number of neutrons. I.e. Number of neutrons = mass number - atomic number

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11
Q

What is nuclide notation?

A

Nuclide notation is a shortened way of displaying the symbol, atomic number and mass number of an atom

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12
Q

What is an isotope?

A

Each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei, and hence differ in atomic mass.

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13
Q

What is the relative atomic mass of an element?

A

It is the average mass of the element’s isotopes. Most elements are made up of atoms of different masses (isotopes). The R.A.M gives an indication of the properties of the isotopes that exist for that element

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14
Q

What is an ion?

A

All atoms of the same type are neutral because they have an equal number of protons and electrons (and so their charges cancel each other out). A particle that doesn’t have an equal number of protons and electrons is called an ion. i.e. it is either positively or negatively charged

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15
Q

Are metal ions positive or negative?

A

ALL metal ions carry a positive charge. They achieve this by losing electrons

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16
Q

Are non-metal ions positive or negative?

A

MOST non-metal ions are negatively charged. This is achieved by gaining electrons.

Note; negative atoms always end in -ide e.g. Nitride

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17
Q

What is a compound?

A

A substance made up of atoms of more than 1 element

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18
Q

Energy is required to separate elements in a compound because the atoms are chemically joined by bonds. What are the 3 types of bonds?

A

Non-metals = covalent bond
Metals = metallic bond
Metal + non-metal = ionic bond

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19
Q

What is a molecule?

A

A group of non-metal atoms held together by covalent bonds. The number and types of atoms present in a molecule gives the chemical formula e.g. H2O

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20
Q

What are the diatomic elements?

A

I Bring Clay For Our New House - Iodine, Bromine, Chlorine, Fluorine, Oxygen, Nitrogen, Hydrogen. These 7 elements are all non-metals and exist as small molecules

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21
Q

What are the 4 common shapes of molecules?

A

Linear (in a line)
Angular (v-shaped)
Pyramidal
Tetrahedral

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22
Q

When atoms join through covalent bonding to form a molecule they become more stable. What do the atoms involved share?

A

Electrons

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23
Q

Why are noble gases very stable?

A

They are stable and unreactive because they have a full outer energy level and so don’t require sharing of electrons

24
Q

What is polar covalent bonding?

A

If the atoms of a covalent bond are different types (metal and non-metal) then the distribution of electrons becomes uneven and one atom ends up having the electrons closer to its own nucleus. This causes an uneven distribution of charge and produces a polar covalent bond

25
Q

How does ionic bonding differ to polar covalent bonding?

A

Unlike in polar covalent bonding, the metal and non-metal atoms don’t share their electrons. They either lose electrons or gain them to become stable

26
Q

Of metal and non-metal atoms, which gain electrons and which lose electrons in an ionic bond?

A

Metal atoms lose electrons forming a positively charged ion

Non-metal atoms gain electrons to form a negatively charged ion

27
Q

What is metallic bonding?

A

Metallic substances are made up of many positively charged ions with wandering (delocalised) electrons. The attraction of the positive metal ions to the delocalised electrons forms a metallic bond

28
Q

What is electricity?

A

The flow of electrons in a definite direction

29
Q

Do metals conduct or insulate electricity?

A

They conduct. Non-metals insulate

30
Q

Why are metals able to conduct?

A

The charged delocalised electrons within the metallic substance are able to flow, giving rise to conduction of electricity

31
Q

What is electrolysis?

A

The process of splitting an ionic solution or melt using electricity. (Electro = electricity, lysis = splitting)

32
Q

What are ions that can move within an ionic solution or melt called?

A

Electrolytes

33
Q

The colour of a compound is linked to the colour of the atoms and bonding within it. This isn’t a question, just an info slide. Flip over for more.

A

Many covalent compounds are colourless. Transition metal ions are often coloured and so ionic compounds are normally coloured.

34
Q

What do the melting and boiling points of a substance indicate about the chemical bond?

A

They indicate the strength of the chemical bond

35
Q

In general, do metals have high or low melting and boiling points?

A

They have high for both and are solid at room temperature

36
Q

What metal is the exception to this and is a liquid at room temperature?

A

Mercury

37
Q

Do ionic substances have high or low M.P and B.P?

A

High. They are also solid at room temperature

38
Q

Do covalent molecular substances have high or low M.P and B.P?

A

Tend to be low and are either liquids or gases at room temperature

39
Q

What is a solution?

A

A solution is made when a solute dissolves in a solvent

40
Q

What is the most common solvent?

A

Water

41
Q

Some substances are not soluble in water and so must be dissolved in non-aqueous solvents e.g. ethanol. Give examples of everyday solutes which are insoluble in water?

A

Paints, nail polish, etc.

42
Q

Are ionic compounds generally soluble in water or not?

A

They are soluble in water

43
Q

Are covalent compounds generally soluble in water or not?

A

No. They are soluble in non-aqueous solvents

44
Q

What is the pH of acids, alkalis and neutral substances?

A

Acid - pH < 7
Alkali - pH > 7
Neutral - pH = 7

45
Q

All acids and alkalis can be identified using chemicals called indicators. What happens with the best indicators when they come into contact with acids, alkalis and neutral substances?

A

There is a clear colour change

46
Q

Are acid solutions ionic or not and what is their charge?

A

All acid solutions are ionic and have a positive charge

47
Q

What is an equilibrium reaction?

A

Equilibrium reactions are said to be reversible reactions. When at equilibrium. the concentration of the reactants is said to be constant, although not necessarily equal

48
Q

Water is a neutral solution. Why is this?

A

Pure water has an equal concentration of hydrogen ions and hydroxide ions when at equilibrium

49
Q

How can the concentration of a solution be determined?

A

If the volume of the solvent and the number of moles of solute are known

50
Q

What type of reaction occurs when acids and alkalis are combined?

A

Neutralisation reaction

51
Q

Describe what happens in a neutralisation reaction?

A

When the acid reacts with the alkali, the acid’s hydrogen ions and the alkali’s hydroxide ions react to form a neutral water solution

52
Q

What is a salt?

A

A substance which contains metal ions and negative ions of an acid. It is formed from the reaction of an acid with an alkali. I.e. Acid + Alkali –> Water + salt

53
Q

What is produced when an acid is combined with a metal carbonate?

A

Acid + Metal carbonate –> Water + Salt + Gas

54
Q

What is a base?

A

A substance that reacts with an acid to form salt and water

55
Q

What are volumetric titrations used for?

A

An experimental procedure used to determine the concentration of an acid or alkali

56
Q

How are volumetric titrations performed?

A

A known volume and concentration of an alkali is titrated against an acid until an end point is reached. Once the end point is known, the concentration of the acid can be determined by using the volume and concentration of alkali used to neutralise it

Chemistry (2 decks)

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