Key concepts in chemistry (1+2) Flashcards

1
Q

What was the first

atomic model?

and in what year was this created?

A

Dalton’s solid atom model:
all atoms of an element are identical; different elements have different atoms

1803

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2
Q

When was the electron discovered?

and by who?

A

1897

Thomson

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3
Q

What atomic model followed the

discovery of the electron?

and in what year was this created?

A

Thomson’s plum pudding model:
atoms are spheres of positive charge with negative electrons dotted around inside

1904

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4
Q

What atomic model followed the

plum pudding model?

and in what year was this created?

A

Rutherford’s solar system model:
atoms have a positive nucleus surrounded by negative electrons in orbits

1911

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5
Q

What atomic model followed the

solar system model?

and in what year was this created?

A

Bohr’s electron shell model:
electrons occupy shells or energy levels around the nucleus

1913

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6
Q

When was the proton discovered?

and by who?

A

1918

Rutherford

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7
Q

When was the neutron discovered?

and by who?

A

1932

Chadwick

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8
Q

What is the

relative mass of an electron?

A

1/1836

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9
Q

Define

mass number.

A

the total number of protons and neutrons in the nucleus of an atom

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10
Q

Define

atomic number.

A

the number of protons in the nucleus

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11
Q

Define

isotope.

A

an atom of an element with the same number of protons but different numbers of neutrons

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12
Q

Define

electronic configuration.

A

the arrangement of electrons in shells in an atom or ion

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13
Q

Define

cation.

A

a positively charged ion that is formed when an atom or group of atoms loses one or more electrons

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14
Q

Define

anion.

A

a negatively charged ion that is formed when an atom or group of atoms gains one or more electrons

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15
Q

What is the formula for a

nitrate ion?

A

NO3-

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16
Q

What is the formula for a

carbonate ion?

A

CO32-

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17
Q

What is the formula for a

sulfate ion?

A

SO42-

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18
Q

What is the formula for a

hydroxide ion?

A

OH-

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19
Q

What is the formula for a

phosophate ion?

A

PO43-

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20
Q

What is the formula for an

ammonium ion?

A

NH4+

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21
Q

What are

ionic bonds?

A

strong electrostatic forces of attraction between oppositely charged ions

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22
Q

What structure do the

ions in an ionic compound form?

and what does this consist of?

A

a giant lattice structure

this has:
- a regular arrangement of ions
- ionic bonds between oppositely charged ions

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23
Q

What are the usual melting and boiling points of

ionic compounds?

and why?

A
  • high melting points
  • high boiling points

this is because there are many strong ionic bonds and large amounts of energy must be transferred to the lattice structure to break these bonds

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24
Q

Are ionic compounds usually soluble in water?

A

yes

they dissolve to form aqueous solutions

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25
Q

Define

covalent bond.

A

the electrostatic attraction between a shared pair of electrons and the nuclei of the two bonded atoms

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26
Q

What are some characteristics of

covalent bonds?

(3)

A
  • strong
  • form between non-metal atoms
  • often produce **molecules **
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27
Q

Define

simple molecule.

A

a molecule consisting of just a few atoms, joined to eachother by strong covalent bonds

28
Q

What are the characteristics of

simple molecular substances?

(3)

A
  • low melting and boiling points
  • do not conduct electricity
  • usually insoluble in water
29
Q

Why can’t

simple molecular substances conduct electricity?

A

their molecules are not electrically charged and do not contain electrons that are free to move

30
Q

Define

intermolecular forces.

A

the weak attractive forces between molecules

31
Q

What are some key characteristics of

diamond?

(5)

A
  • it is an allotrope of carbon
  • each carbon atom is bonded to four others
  • there are strong covalent bonds between atoms
  • it has a regular lattice structure
  • it is a giant covalent structure
32
Q

What are some key properties of

diamond?

(4)

A
  • high melting and boiling points
  • insoluble
  • cannot conduct electricity
  • very hard
33
Q

What are some key characteristics of

graphite?

(6)

A
  • it is an allotrope of carbon
  • each carbon atom is bonded to three others
  • there are strong covalent bonds between atoms in a layer
  • there are weak intermolecular forces between layers
  • it has a regular lattice structure
  • it is a giant covalent structure
34
Q

What are some key properties of

graphite?

(4)

A
  • high melting and boiling points
  • insoluble
  • can conduct electricity
  • soft
35
Q

What are some key characteristics of

graphene?

(6)

A
  • it is an allotrope of carbon
  • each carbon atom is bonded to three others
  • there are strong covalent bonds between atoms
  • it’s structure resembles a single layer of graphite
  • it has a regular lattice structure
  • it is a giant covalent structure
36
Q

What are some key properties of

graphene?

(4)

A
  • it can conduct electricity
  • it is very strong
  • it is very flexible
  • it is almost transparent

(as its layers are just one atom thick)

37
Q

What are some key characteristics of

buckminsterfullerene?

(5)

A
  • it is an allotrope of carbon
  • each carbon atom is bonded to three others
  • there are strong covalent bonds between atoms
  • the carbon atoms are arranged in pentagons as well as hexagons
  • it is a giant covalent molecule
38
Q

What are some key properties of

buckminster fullerene?

(3)

A
  • it is a semi-conductor
  • it is insoluble
  • it has high melting and boiling points
39
Q

What are some key characteristics of

nanotubes?

(6)

A
  • they are allotropes of carbon
  • each carbon atom is bonded to three others
  • there are strong covalent bonds between atoms
  • they are hollow
  • they can have closed ends or open ends
  • they can be several mm long
40
Q

What are some key properties of

nanotubes?

A
  • they can conduct electricity
  • they are very strong
  • they have high melting and boiling points
  • they are insoluble
41
Q

What are some

typical physical properties of metals?

think:
- appearance?
- electrical conductivity?
- density?
- melting point?
- malleability?

A
  • shiny
  • good conductors
  • high density
  • high melting point
  • malleable

mercury is an exception, it is liquid at room temperature

42
Q

What are some

typical physical properties of non-metals?

think:
- appearance?
- electrical conductivity?
- density?
- melting point?
- malleability?

A
  • dull
  • poor conductors
  • low density
  • low melting point
  • brittle

diamond and graphite are exceptions, they both have very high melting points, graphite conducts electricity

43
Q

What is the general structure of a

metal?

A

a giant lattice of positively charged metal ions in a sea of delocalised electrons

44
Q

Define

metallic bond.

A

strong electrostatic forces of attraction between positive metal ions and delocalised electrons

45
Q

Define

empirical formula.

A

the simplest whole number ratio of atoms of each element in a compound

this does not show how the atoms are arranged or (usually) the actual number of atoms

46
Q

Define

molecular formula.

A

the number of atoms of each element

this does not show how the atoms are arranged

47
Q

Define

structural formula.

A

the number of atoms of each element

this does give an idea of how they are arranged

48
Q

What does a

drawn structure

not show?

(2 things)

A
  • the molecule’s three-dimensional shape
  • the bonding and non-bonding electrons
49
Q

What do

ball and stick models

show?

(2 things)

A
  • how each atom is bonded to other atoms
  • the molecule’s three-dimensional shape
50
Q

What do

ball and stick models

not show?

(2 things)

A
  • the bonding and non-bonding electrons
  • each element’s chemical symbol
51
Q

What are the positives and negatives of

space-filling models

instead of ball and stick models?

(1+, 1-)

A

+they more accurately represent the sizes of atoms relative to their bonds
-you may not be able to see all the atoms in a complex space-filling model

52
Q

What is

relative formula mass?

A

the mass of a molecule or unit of a substance compared with 1/12th of the mass of a Carbon 12 atom

53
Q

Describe an experiment to determine an

empirical formula.

(9 steps)

A
  1. Measure and record the
    mass of an empty crucible with its lid.
  2. Put a length of magnesium ribbon into the crucible.
  3. Measure and record the total mass of the crucible, its lid and contents.
  4. Place the crucible on a tripod with a pipe clay triangle. Strongly heat the crucible for several minutes using a Bunsen burner.
  5. When the magnesium has stopped glowing, turn off the Bunsen burner and allow the crucible to cool down.
  6. Measure and record the total mass of the crucible, its lid and contents.
  7. Calculate the** mass of magnesium** used.
  8. Calculate the mass of oxygen gained.
  9. Calculate the empirical formula of magnesium oxide.
54
Q

Define

closed system.

A

a situation in which no substances can enter or leave during a reaction

55
Q

Define

open system.

A

a situation in which substances can enter or leave during a reaction

56
Q

Define

stoichiometric equation.

A

a balanced chemical equation

57
Q

When is a reactant

in excess?

A

when there is enough:
- to react with all the other reactant
- for some of it to be left over when the reaction stops

the other reactant is the limiting reactant

58
Q

How does the

limiting reactant affect the mass of product?

A

the mass of product formed is controlled by the mass of the reactant that is not in excess: the reaction continues until all the particles of the limiting reactant have been used up

59
Q

Define

solution.

A

a mixture of a solute in a solvent

60
Q

Define

solute.

A

the substance that dissolves

61
Q

Define

solvent.

A

the substance that the solute dissolves in

62
Q

What equation links

mass, volume and concentration?

A

mass = concentration x volume

m = CV

m: grams, g
C: grams per cubic decimetre, g/dm3
V: cubic decimetre, dm3

63
Q

What is

avogadro’s constant?

(to three significant figures)

A

6.02 x 10^23

64
Q

What equation links

relative formula mass, moles and mass?

A

moles = mass/RFM

n = m/Mr

n: moles, mol
m: grams, g

65
Q
A