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Principles of chemistry Flashcards

(53 cards)

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1
Q

Describe a solid
(refer to arrangement, movement, and energy of particles.

A

• Strong forces of attraction between particles hold them close together in fixed position
• Forms a lattice arrangement
• Particles vibrate in fixed position

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2
Q

Describe a liquid
(refer to arrangement, movement, and energy of particles.

A

• Weak forces of attraction between particles, randomly arranged and free to move past each other, but stick closely together
• Particles are constantly moving with random motion

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3
Q

Describe a gas
(refer to arrangement, movement, and energy of particles.

A

• Very weak forces or attraction between particles
• Free to move and are far apart
• Particles move constantly with random motion

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4
Q

What physical changes require heat supplied, and why?

A

Melting :
• makes particles vibrate more, which weakens the forces that hold the solid together
• at a certain temperature, the particles have enough energy to break free from their positions

Evaporation:
• Makes particles move faster, which weakens and breaks the bonds holding the liquid together
• At a certain temperature the particles have enough energy to break the bonds

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5
Q

What physical changes require heat to be given out, and why?

A

Freezing:
• The particles lose kinetic energy
• Eventually stuck in fixed position

Condensing:
• The particles lose kinetic energy, so the move slower

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6
Q

Define Solution

A

A mixture of a solute dissolved in a solvent

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7
Q

Define solute

A

Substance being dissolved

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8
Q

Define solvent

A

liquid in which a solute dissolves in

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9
Q

Define saturated solution

A

A solution in which no more solvent can be dissolved

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10
Q

Difference between:
•element
•compound
•mixture

A

• Substance made from only one type of atom
• Substance made from 2 or more elements that have reacted chemically with each other
• Consists of 2 or more elements or compounds not chemically combined together

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11
Q

Explain a pure substance

A

• A single element or compound, not mixed with any other substance
• Boils and melts and specific temperatures

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12
Q

Simple distillation

A

• used to separate a solvent from a solution

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13
Q

Fractional distillation

A

• used to separate a pure liquid from a mixture of liquid
° this works because they have different boiling points

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14
Q

filtration

A

• used to separate an insoluble solid from a liquid or solution

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15
Q

crystalisation

A

• used to separate a soluble salt from a liquid or solution

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16
Q

Chromatography

A

• used to separate mixtures of soluble substances (usually ink, dye etc)

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17
Q

How to find the Rf value

A

Rf value = distance moved by substance / distance moved by solvent

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18
Q

What is an atom

A

• The smallest piece of an element that can exist
• all substances made from atoms
• a substance with only one type of atom = element

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19
Q

What is a molecule

A

formed when atoms join together by chemical bonds (can be same element)

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20
Q

Where do you find protons in an atom?

A

in the nucleus

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21
Q

Where do you find neutrons in an atom?

A

in the nucleus

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22
Q

Where do you find electrons in an atom?

Study These Flashcards
A

in the shells around the nucleus

23
Q

what is the atomic number

Study These Flashcards
A

the number of protons

24
Q

what is the mass number

Study These Flashcards
A

number of protons + number of neutrons

25
what is an isotope
different atoms of the same element that have the SAME number of protons but DIFFERENT number of neutrons
26
what is the relative atomic mass (Ar)
an average value that takes account of the abundance of isotopes of the element
27
How to find the relative atomic mass of an element
R.A.M. = (mass of isotope A × % of isotope A) + (mass of isotope B × % of isotope B) / 100
28
How are elements arranged in periodic table
* arranged in order of atomic number * elements with similar properties in the same group * same group = same number of electrons in outer shell * same period = same number of shells
29
What does the electronic configuration of an element tell you
* how many electrons are in each shell around an elements nucleus * KEY : 1st shell holds 2 electrons, 2nd and 3rd shells holds 8.)
30
How to classify elements as metals or non-metals
* metals are usually conduct electricity * non-metals are not conductive ( except graphite) * If an element is conductive and its oxide is basic = metal * If an element is not conductive and oxide is acidic = non-metal
31
How does the electeonic configuration of a main group element relate to its position in the periodic table
• group number = gives number of electrons in outer shell • period = gives number of electeon shells
32
why do elements in the same group of the periodic table have similar chemical properties
• number of elections in outer shell is responsible for the way elements react • elements with same numbe rof electrons in the outer shell will have similar reactions • elements in the same group have similar chemical properties
33
why do noble games not react
• they have a full outer shell • they are unreactive because they have a stable arrangement of electrons
34
How to calculate relative formula masses
the sum of the relative atomic masses of the atoms present
35
what is the formula for moles
moles = mass / Ar
36
formula for percentage yield
percentage yield = (actual yield/ theoretical yield) ×100
37
define empirical formula
the simplest whole number ratio of atoms of each element in a compound
38
define molecular formula
the number of atoms of each element in a compound
39
how are ions formed
• atoms that have lost or gained electrons • metal and non metal reacting • electrons are transferred from outer shell
40
define cation
positive ion
41
define anion
negative ion
42
describe ionic bonding
• a giant structure of ions = ionic compound • held together by stong electrostatic forces of attraction between oppositely charged ions • The forces act in all directions in the lattice
43
why do compounds with giant ionic lattice have high mpt and bpt
• srong electrostatic forces of attraction between oppositely charged ions • needs alot of energy to overcome these forces of attraction
44
when do ionic compounds conduct electricity
• in solid ions are in fixed positions, so they can't conduct electricity • when molten or in aqueous solution, ions are free to move carrying charge and conduct electricity
45
how is a covalent bond formed
• between non metals • atoms share electrons
46
describe covalent bonds
• strong covalent bonds between atoms • electrostatic attraction between positive nuclei of atoms and pairs of negative electrons that are shared between them
47
explain why substances with a simple molecular structure are gases, liquids or solids with low mpt and bpt
• substances with small molecules are usually gases or liquids that have low mpt and bpt • substances with small molecules have weak intermolecular forces between molecules. These are broken in boiling or melting • substances with small molecules don't conduct electricity because small molecules do not have an overall electric charge
48
why do the mpt and bpt of substances with simple molecular structures increase with increasing relative molecular mass
• intermolecular forces increase with the size of the molecules • so larger molecules have higher mpt and bpt
49
why are substances with giant covalent structures solids with high mpt and bpt
• all the atoms are linked to other atoms by stong covalent bonds • these bonds require alot of energy to overcome and melt or boil these substances
50
explain the how the structure of diamond influence its physical properties
• each carbon is joined to 4 other carbon covalently • it's very hard • has high mpt • does not conduct electricity
51
explain the how the structure of graphite influence its physical properties
• each carbon is bonded to 3 other carbon • forms layers of hexagonal rings • layers can slide over eachother because there are no covalent bonds between layers • graphite is soft and slippery • one epectron from each carbon is delocalised • it can conduct electricity
52
explain the how the structure of C⁶⁰ fullerene influence its physical properties
• 60 carbon atoms, each carbon bonded to three others • forms hexagons and pentagon • softer than diamond but harder than graphite • does not conduct electricity well
53
do covalent compounds conduct electricity
NO except for graphite and graphene

Chemistry (5 decks)

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