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Chemistry > Chemistry 2 > Flashcards

Chemistry 2 Flashcards

1
Q

What is the Mass Number?

A

Total number of protons and neutrons. (top number)

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2
Q

What is the Atomic Number?

A

Number of protons. (Bottom number)

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3
Q

What is the mass of proton, electrons and neutrons?

A

1) Proton - 1
2) Electron - very small
3) Neutron - 1

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4
Q

What is an element, compound and mixture?

A

Element - a substance on the periodic table. Only one type of atom.
Compound - atoms of two or more elements are chemically bonded.
Mixture - atoms of two or more elements are together (however not chemically bonded).

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5
Q

What is an isotope?

A

Isotopes are different atomic forms of the same element, which have the same number of protons but a different number of neutrons.

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6
Q

What is an ion?

What is an ionic bond?

A

An ion is a charged atom that has lost or gained one or more electrons.

An ionic bond is strong electrostatic forces between ions. Its between a metal and non metal.

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7
Q

What’s an Ionic compound structure like?

What similar properties are there in ionic compounds?

A

They have a giant ionic lattice where the ions form closely packed in a regular lattice arrangement.

Have high melting and boiling points due to strong attraction between the ions. It takes huge amounts of energy to break these bonds.

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8
Q

How does a metal conduct electricity?

A

The electrons on the outer shell (high amounts of energy) of the metal are delocalised (free) and are able to move about to conduct electricity.

Current - electrons or ions moving

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9
Q

Why do covalent substances have relatively low melting and boiling points?

A

They have weak intermolecular forces of attraction between the molecules. It is these intermolecular forces that are overcome when boiling or heating something, not the strong covalent bonds.

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10
Q

Why do ionic compounds have high melting and boiling points?

A

Ionic compounds have strong electrostatic forces in all different directions between opposite attracted ions. This requires lots of energy to break these strong bonds.

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11
Q

Can an ionic substance conduct electricity?

A

No.

However when they are melted or dissolved in water they can. This is because the ions are free to move and carry the current.

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12
Q

What is covalent bonding?

A

When electron shells overlap and electrons are shared between atoms. This is between two non-metals.

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13
Q

What is diamond made out of?

A

It has carbon atoms in a giant covalent structure, for every carbon there are four covalent bonds.

This makes diamond very hard and it can’t conduct electricity or heat.

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14
Q

What is graphite made out of?

A

This has only carbon atoms with every carbon atoms bonds to three others, forming layers. The layers mean that it can slide over each other as there are no covalent bonds making graphite soft and slippery.

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15
Q

What is an allotrope?

What two different allotrope’s does carbon have?

What is a shape memory alloy?

A

The existence of elements in two or more different forms.

Diamond and Graphite.

A alloy that can return to its original shape after being deformed.

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16
Q

Can graphite conduct electricity and heat?

A

Each carbon atom has one electron which is not involved in the bond and is delocalised. This means that graphite can conduct electricity and heat because the electrons can move.

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17
Q

Polymers

Two types of poly(ethene)

A

The polymer you make depends on the monomers and the conditions its made with.

Low density (LD) and high density (HD)

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18
Q

What is the relative atomic mass? (Ar)

What is the relative formula mass? (Mr)

A

The mass number

The Mr of a compound is the sum of the relative atomic masses.

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19
Q

What is a mole?

How do I find out the number of moles?

A

The Ar or Mr of a substance in grams.

Number of moles = mass/Mr

For example: How many mole are there in 42g of carbon?
42/12 = 3.5 moles

20
Q

How do you find out the empirical formula?

A

ask miss

21
Q

How can elements and compounds be detected?

What are the advantages?

What can chemical analysis identify?

A

Using instrumental methods.

They are accurate, sensitive and rapid and useful when there is a small amount of the sample.

Additives in food. Artificial colours can be detected by paper chromatography.

22
Q

What is Gas Chromatography?

How does it work?

A

Detects elements and compounds.

  1. The sample is injected and is carried around by gas through a column. Solid particles are in the column to separate the sample.
  2. The different mass of different particles mean they come in the detector at different times.
  3. Then the information goes on the computer. The position of the peaks on the output indicates the retention time and the number of peaks shows the number of compounds present.
23
Q

What is a gas chromatography column linked to?

A

The mass spectrum. It can give you the relative molecular mass of each substance and the pattern can match it against the database of known compounds stored in the computer.

24
Q

Empirical Formula

A 
                   Ar of element

Then divide each answer by the smallest number.

25
Q

What is atom economy and how do you find it?

Yeild

A

The atoms move into the useful product
AE= Mr in useful product/ Mr in all reactants of product x 100

How much useful product you make from what you start with.

26
Q

Reversible Reactions

A

In some reactions, the products of the reaction can react to produce the orginal product.
A + B (Reversible Sign) C + D

For Example;

Ammonium chloride (RS) ammonia + hydrogen chloride

27
Q

The three important things to remember about nano-science?

A

write something for this

28
Q

How do you find the rate of reactions?

A 
          time
         time
29
Q

Why does increasing the temperature, increase the rate of reaction?

A

It increases the speed of the particles because of its kinetic energy, which makes them collide more frequently. The more collisions (if they have enough energy between the them) means more reactions.

30
Q

Why does increasing the concentration, increase the rate of reaction?

A

An increased concentration will mean more particles in that area, so frequent collisions will happen, increase the rate of reaction.

31
Q

Why does increasing the surface area, increase the rate of reaction?

A

Increasing the surface area exposes more particles, so the frequency of collisions will increase.

32
Q

Why does increasing the pressure, increase the rate of reaction?

A

Increasing the pressure means creating a smaller volume, when there is a smaller volume there are more frequent collisions between the particles.

33
Q

What is an exothermic reaction?

What are some examples?

A

It transfers the energy into its surroundings. (usually in the form of heat and shown in rise of temperature)

Good example;

  • Burning fuels (Combustion)
  • neutralisation reactions (acid and alkali)

Day to day examples:

  • selfheating cans
  • hand warmers
34
Q

What is an endothermic reaction?

What are some examples?

A

It takes in energy from its surroundings.

Good examples;
- thermal decomposition
- some sports injury packs
this is because they take in the heat around it making it cold.

35
Q

How does endothermic and exothermic reactions come into play in reversible reactions?

A

If the reaction is exothermic in one directions, it will be endothermic in the other direction.

36
Q

What are the state symbols in equations?

A

Solid - (s)
Liquid - (l)
Gas - (g)
Aqueous Solution - (aq)

37
Q

What is an acid?

A

Substances that produces hydrogen ion when we add water to them.

38
Q

What is a base?

A

It’s a metal oxide or a metal hydroxide, it will neutralise acid to make salt water.

39
Q

What is an alkali?

A

It’s a soluble hydroxide, they produce hydroxide ions. All alkali’s are bases but not all bases are alkali’s.

40
Q

What three ways can soluble salts by reacting them with acid?

A

Metals - however some are too reactive and some aren’t reactive enough.

Insoluble bases – it’s added to the acid
until no more will react and the excess solid is
filtered off

Alkali - an indicator can be used to show whether the alkali and acid has completely reacted to produce a salt solution.

41
Q

How can insoluble salts be made?

A

Insoluble salts can be made by mixing appropriate
solutions of ions so that a precipitate is formed.

Precipitation can be used to remove unwanted
ions from solutions, for example in treating water
for drinking or in treating effluent.

42
Q

Acid + Alkali ==>

Acid + Base ==>

Metal + Acid ==>

A

water + salt

water + salt

metal salt + hydrogen

43
Q

What does ammonia produce when it dissolves in water?

A

It produces an alkaline solution, it is used to produce ammonia salts.

They are important as fertilisers.

44
Q

Hydrogen ion makes solutions…

Hydroxide ions make solutions…

A

Acidic

Alkaline

45
Q

What happens in neutralisation reactions?

A

Hydrogen ions react with hydroxide ions to produce

water.

Chemistry (3 decks)

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