Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

(21) Chemistry 2 > Key Concepts > Flashcards

Key Concepts Flashcards

You may prefer our related Brainscape-certified flashcards:
Periodic Table flashcards Chemistry 101 flashcards AP® Chemistry flashcards Organic Chemistry 101 flashcards
1
Q

How did the atomic structure theory change?

A
  • Dalton model (atoms as solid spheres)
  • Plum pudding model (Thomson measurements of charge/mass showed electrons - positively charged pudding with electrons floating in)
  • Nuclear atom (gold foil experiment showed alpha particles deflected - showing positive nucleus)
  • Bohr model (introduced shells - atom would collapse in nuclear model as nucleus would attract electrons)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the Relative mass of an electron?

A

0.0005

should know mass and charge of all the others

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How big is an atom?

A

10^-10 m (ten to the minus ten)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is an isotope?

A

Different forms of the same element - have the same number of protons but a different number of neutrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is an example of an isotope?

A

Carbon-12 and Carbon-13

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the RAM?

A

Relative Atomic Mass - average mass of an atom - isotopes make it decimal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How can the Ar be worked out from isotopic abundances?

A
  • Multiply each isotopic mass by its isotopic abundance (given in Q) - add up the results
  • Divide by the sum of the abundances (given in Q)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Who made the first periodic table?

A

Mendeleev (1869)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How did Mendeleev arrange elements?

A

Into groups based on similar properties - as he did this he realised he could put them in order of atomic mass and a pattern occurred - elements with similar properties could be put in columns - however some elements didn’t fit the pattern so he switched some around so he could keep them in the right columns - also left gaps to keep elements with similar properties together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How did Mendeleev predict undiscovered elements?

A

He used properties of of other elements in the columns with the gaps to predict the properties of undiscovered elements

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What did John Dalton describe atoms as?

A

Solid spheres - different spheres made up different elements

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How did Dalton’s ideas about atoms change?

A

JJ Thomson discovered from his measurements of charge and mass, that atoms must contain electrons - led to plum pudding model, positively charged atom with electrons loose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What did Rutherford do?

A

Conducted the gold foil experiment - positively charged alpha particles fired at a thin sheet of gold - some particles passed through but some were deflected backwards - theory of nuclear atom, positively charge nucleus surrounded by cloud of negative electrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What did the Bohr Model do?

A

Put the electrons into shells - as the cloud of electrons would be attracted to the nucleus and collapse

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the relative charge and mass of an electron?

A

Mass - 0.0005

Charge - -1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the relative charge and mass of a proton?

A

Mass - 1

Charge - +1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the relative charge and mass of a neutron?

A

Mass - 1

Charge - 0

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what does aqueous mean?

A

dissolved in water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what is the chemical formula for water?

A

H2O

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what is the chemical formula for carbon dioxide?

A

CO2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what is the chemical formula for chlorine?

A

Cl2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what is the chemical formula for ammonia?

A

NH2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what is the chemical formula for hydrogen?

A

H2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what is the chemical formula for oxygen?

A

02

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

what is the formula for an ammonium ion?

A

NH4+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

what is the formula for a nitrate ion?

A

NO3-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

what is the formula for a sulfate ion?

A

SO4 ²-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

what is the formula for a hydroxide ion?

A

OH-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

what is the formula for a carbonate ion?

A

CO3 ²-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

what is included in an ionic equation?

A
  • only the reacting particles (and the products they form)
  • so when writing out the equation cross out anything that’s the same on both sides
  • e.g. 2Na -> 2Na wouldn’t be included (but the chemicals which reacted together would)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

do you understand how to write ionic equations in general?

A

pg 76

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

what is a hazard?

A

a hazard is anything that has the potential to cause harm or damage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

what is a risk?

A

the probability or someone being harmed if they are exposed to a hazard

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

what does oxidising mean?

A

provides oxygen which allows other materials to burn more fiercely (symbol - circle with fire on like a hat)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

what does harmful mean?

A

can cause irritation, reddening or blistering of the skin (symbol - !)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

what does environmental hazard mean?

A

harmful to organisms and to the environment (fish and tree symbol)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

what does highly flammable mean?

A

catches fire easily (fire symbol)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

what does toxic mean?

A

can cause death (e.g. swallowing, breathing in, absorption through skin) (skull symbol)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

what does corrosive mean?

A

destroys materials, including living tissues (e.g. eyes, skin) (test tube and hand symbol)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

give an example of an oxidising substance

A

liquid oxygen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

give an example of a harmful substance

A

bleach

42
Q

give an example of an environmental hazard

A

mercury

43
Q

give an example of a highly flammable substance

A

petrol

44
Q

give an example of a toxic substance

A

hydrogen cyanide

45
Q

give an example of a corrosive substance

A

concentrated sulfuric acid

46
Q

a student is carrying out an experiment using two chemicals.
chemical A is corrosive while chemical B is highly flammable. suggest appropriate safety precautions the student could take to minimise the risk associated with the chemicals.

A

the student should wear gloves, a lab coat and goggles when handling chemical A (1 mark)
when handling chemical B the student should take care to keep it away from naked flames (1 mark)

47
Q

How is the modern periodic table organised?

A
  • Organised in order of ascending atomic number once protons/electrons discovered (fit the same patterns that mendeleev worked out)
  • Elements with similar chemical properties form groups (columns)
  • The group corresponds to the number of electrons in the outer shell (so group 7 elements have 7 electrons in outer shell)
  • Rows are called periods (correspond to the number of shells of electrons an element has e.g. period 3 has 3 shells)
48
Q

What are energy levels?

A

Shells (on atoms)

49
Q

What is the electronic configuration of argon (18 electrons)?

A

2.8.8

50
Q

What are ions?

A

Charged particles that form when atoms lose or gain electrons (to obtain a stable electronic structure)

51
Q

When do negative ions form?

A

anions - form when atoms gain electrons

52
Q

When do positive ions form?

A

cations - form when atoms lose electrons

53
Q

What is the charge if 2 electrons are lost?

A

2+

54
Q

Which elements form ions most readily?

A

Groups 1 & 2 and 6 & 7

55
Q

What ions do group 1 and 2 elements form?

A

Group 1 = 1+ ions (cations)
Group 2 = 2+ ions (cations)
- they are metals and they lose electrons to form positive ions

56
Q

What ions do group 6 and 7 elements form?

A

Group 6 = 2-
Group 7 = 1-
- they are non-metals and will gain electrons to form negative ions

57
Q

What are ionic compounds?

A

Compounds made up of a positively charged part and a negatively charged part - but the overall charge is zero so the charges are balanced

58
Q

What are ions with names ending in -ate (e.g. nitrate)?

A

negative ions containing oxygen and at least one other element

59
Q

What are ions with names ending in -ide (e.g. chloride)?

A

Negative ions containing only one element (apart from hydroxide OH-)

60
Q

How do you work out the formula of an ionic compound (e.g. calcium nitrate)?

A
  1. write out the formulas of the ions present
    (Ca²+, NO3-)
  2. overall charge must be zero so work out the ratio that gives a neutral charge
    (Ca(NO3)2)

pg 93

61
Q

What are the three types of bonding in particles?

A

ionic, covalent and metallic

62
Q

When does ionic bonding occur?

A

When a metal and a non-metal react - the metal atom loses electrons (forming a cation) and non-metals gain these electrons - forming anions - these oppositely charged ions are strongly attracted to eachother by electrostatic forces (called an ionic bond)

63
Q

Do you know how to draw ionic compounds using dot and cross diagrams?

A

(with the square brackets around the compounds that have been formed)

64
Q

What structure do ionic compounds have?

A

A regular lattice structure - very strong electrostatic forces of attraction (between oppositely charged ions)

65
Q

Give an example of a giant ionic lattice

A

Sodium chloride

66
Q

What are the properties of ionic compounds?

A
  • High melting/boiling points (due to strong attraction between ions takes large amount of energy to overcome)
  • do not conduct electricity (ions fixed in place)
  • melted ionic compounds have free moving ions so an electrical current can be carried
  • many dissolve easily in water - ions separate so can carry electrical current
67
Q

What are the advantages and disadvantages of using 2D representations of atoms?

A
  • simply shows the atoms something contains
  • shows how the atoms are connected
  • don’t show shape of the substance
  • don’t give idea of the size of atoms
    (e. g. displayed formulas)
68
Q

What are the advantages and disadvantages of using dot and cross diagrams to show atoms?

A
  • show how compounds/molecules are formed
  • show where electrons go in ions/bonds
  • don’t give ideas about size or arrangement of atoms
69
Q

What are the advantages and disadvantages of using 3D models to show atoms?

A
  • show arrangement of ions

- only show outer layer of substance

70
Q

What are the advantages and disadvantages of using ball and stick models to show atoms?

A
  • help visualise structures (shape of the lattice/molecule in 3D)
  • make it seem like there are gaps between atoms (but this is just where electron clouds interact)
  • dont show correct scales of the atoms and ions (atoms and ions are different sizes)
71
Q

What is a covalent bond?

A

A strong bond that forms when a pair of electrons is shared between two atoms - these bonds make up simple molecular substances

72
Q

Do you know how to draw dot and cross diagrams for…

A
  • H2
  • HCl
  • H2O
  • O2
  • CH4
  • CO2
    (its kinda obvious as long as you know how to draw covalent bonds - with the overlapping circles with the shared electrons inside)
73
Q

How big are simple molecules?

A

10^-10

74
Q

What are the properties of simple molecular structures (made up of covalent bonds)?

A
  • atoms within the molecules are held together by very strong covalent bonds
  • forces of attraction between the molecules are very weak
  • very low melting/boiling points (molecules easily parted as weak forces of attraction)
  • most are gases/liquids at room temp
  • bigger molecules have stronger intermolecular forces (so more energy needed to separate them so boiling point will increase)
  • dont conduct electricity - no free electrons/ions
  • some are soluble in water
75
Q

What are polymers?

A

Molecules made up of long chains of covalently bonded carbon atoms (e.g. polythene)

76
Q

How are polymers formed?

A

When lots of small molecules (called monomers) join together

77
Q

What are the properties of giant covalent structures?

A
  • all atoms are bonded to each other (by strong covalent bonds)
  • very high melting/boiling points (lots of energy needed to break bonds)
  • dont conduct electricity (as don’t generally contain charged particles)
  • aren’t soluble in water
78
Q

What are some examples of carbon-based giant covalent structures?

A

Diamond, graphite and graphene

79
Q

What are the properties of diamond? (a carbon-based giant covalent structure)

A
  • made up of a network of carbon atoms that each form 4 covalent bonds
  • very high melting point (as the strong covalent bonds take a lot of energy to break)
  • the bonds hold the atoms in a rigid lattice structure, making diamond really hard - used for strengthening cutting tools
  • no free electrons/ions so doesn’t conduct electricity
80
Q

What are the properties of graphite? (a carbon-based giant covalent structure)

A
  • each carbon atom forms 3 covalent bonds (creating sheets of carbon atoms arranged in hexagons)
  • no covalent bonds between layers - only held weakly so are free to move over each other
  • this means graphite is soft and slippery - so used as a lubricating material
  • high melting point (the covalent bonds within the layers need lots of energy to break)
  • carbon has 4 outer electrons - only 3 are used in graphite bonds - so each atom has a delocalised electron - meaning it conducts electricity
81
Q

What are the properties of graphene? (a carbon-based giant covalent structure)

A
  • graphene is one layer of graphite
  • a sheet of carbon atoms joined in hexagons
  • one atom thick sheet makes it two-dimensional
82
Q

What are fullerenes?

A
  • molecules of carbon shaped like closed tubes or hollow balls (so they are hollow)
  • mainly made up of carbon atoms arranged in hexagons (but can contain pentagons or heptagons)
  • used to “cage” other molecules - the fullerene structure forms around another atom (trapping it inside)
  • could be used to deliver a drug directly to cells in the body
  • have huge surface area - could help make great industrial catalysts (individual catalyst molecules could be attached to the fullerenes)
83
Q

What are nanotubes?

A

a type of fullerene - like tiny cylinders of graphene (so conduct electricity) - high tensile strength (stretchy) so used to strengthen materials without adding much weight - e.g. strengthen sports equipment (so it is strong but light)

84
Q

How is metallic bonding formed?

A
  • consist of a giant structure
  • electrons in outer shell are delocalised and shared between atoms - there is a strong electrostatic attraction between these Negative electrons and the Positive metal ions which means that the atoms are held together in a strong, regular structure
  • compounds held together by metallic bonding are metallic elements and alloys
  • lose electrons to gain full outer shell
85
Q

What are the physical properties of metals?

A
  • lots of energy needed to break the strong electrostatic force (between the positive metal ions and the delocalised electrons) - so high melting/boiling points
  • shiny solids at room temp
  • not soluble in water
  • very dense as metallic structure is packed close together
  • malleable - can be hammered/rolled into flat sheets as layers of atoms can slide over each other
  • good conductors of electricity and heat - delocalised electrons carry the current and thermal energy through the material
86
Q

What does it mean if mass is conserved?

A
  • no atoms are destroyed/made during a chemical reaction so there is a same number of atoms on each side of a chemical equation (this can be seen if you do a reaction in a closed system)
87
Q

What is an example of conservation of mass in action?

A

If you do a precipitation reaction:
- copper sulfate + sodium hydroxide react in an airtight test tube on a mass balance to form copper hydroxide (precipitate) + sodium sulfate - the mass doesn’t change

88
Q

Why might the mass appear to increase in a reaction?

A
  • if one of the reactants is a gas found in the air and the products are not gas
  • e.g. when a metal in an unsealed container reacts with oxygen - the mass in the container increases - the mass of metal oxide produced is equal to the total mass of the metal and oxygen that reacted from the air
89
Q

Why might the mass appear to decrease in a reaction?

A
  • if one of the products is gas and the reaction is done in an unsealed reaction vessel
  • e.g. when a metal carbonate thermally decomposes to form a metal oxide + carbon dioxide gas - the gas will escape and the mass will appear to decrease
90
Q

Do you know how to find the relative formula mass of something?

A

(its literally just finding the mass of a compound from adding the masses of the original elements e.g. the mass of MgCl2)

91
Q

What is the difference between the empirical formula and the molecular formula?

A

The molecular formula is the number of atoms in a molecule
The empirical formula is the simplest ratio of atoms
e.g. molecular formula of glucose = C6 H12 O6
empirical formula of glucose + C H2 0

92
Q

How do you use Avogadro’s Constant to calculate the number of particles?

A

no. of particles =

avogadro’s constant x no. of moles

93
Q

What is avogadro’s constant?

A

6.02 x 10^23

94
Q

What is the equation for finding the mass in grams of a compound?

A

mass of compound =

no. of moles x relative atomic mass (or formula mass)

95
Q

How do you find the concentration of a solution?

A

concentration = mass of solute (solid you’re dissolving)

volume of solution

96
Q

How do you calculate the empirical formula?

A
  1. find the atomic mass of the elements involved
  2. divide the mass (g) given in the question by the atomic mass
  3. divide all your answers by the smallest answer
  4. this is your answer - you may need to multiply them all so you get whole numbers
97
Q

How can you use an experiment to calculate the empirical formula of a metal oxide?

A
  1. heat a crucible until red rot (to clean it)
  2. leave the crucible to cool then weigh it
  3. add clean magnesium ribbon to the crucible and reweigh it
  4. heat the crucible containing the magnesium for 10 mins until the ribbon turns white - put on lid to stop any solid escaping but slightly ajar to let in oxygen
  5. allow to cool and weigh again to find the mass of magnesium oxide
    - you can use the masses you found to calculate the mass of oxygen that was used - and in turn the empirical formula
98
Q

What is a limiting reactant?

A

the reactant that is used up in a reaction - the others are said to be in excess

99
Q

How can you calculate the amount of product formed from the limiting reactant?

A
  1. write the balanced equation
  2. work out the atomic masses of the reactant and product you’re interested in
  3. find how many moles there are of the substance you know the mass of
  4. use the balanced equation to work out the no. of moles in the other substance
  5. use the no. of moles to find the mass (pg 94)
100
Q

How can you balance equations using reacting masses?

A

by using the empirical formula

(21) Chemistry 2 (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions