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chemistry > mod 1 > Flashcards

mod 1 Flashcards

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1
Q

what are the properties of a mixture?

A
  • can be separated by physical means
  • composition varies
  • set of properties varies
  • comprises two or more pure substances
  • made of different types of particle groups
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2
Q

what are the properties of a pure substance?

A
  • can’t be separated by physical means
  • constant/definitive composition
  • fixed set of properties
  • made of one type of particle group
  • can be separated by chemical means
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3
Q

homogenous

A
  • uniform in all parts
  • one visible layer
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4
Q

examples of homogenous

A

milk, coins, drill bits

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5
Q

what is a metal alloy?

A

solidified metal mixture that had other elements dispersed through it when molten

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6
Q

examples of alloys

A

steel –> iron & carbon
bronze –> copper & tin
brass –> copper & zinc
solder –> lead & tin

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7
Q

solution

A

solute dissolved in a solvent
- only one layer
- clear/transparent
- aqueous solution referent a solute dissolved in water
- non-aqueous solution doesn’t have water as a solvent

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8
Q

colloid

A

large molecules are evenly spread out through another substance, usually in a liquid the large molecules do not settle over time
- only one layer
- opaque/translucent

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9
Q

heterogenous

A
  • not uniform in all parts
  • more than one visible layer
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10
Q

suspension

A

mixture where combined substances do not dissolve in one another but form layers quickly
- two or more layers of substances
- may be clear translucent/opaque

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11
Q

examples of homogenous mixtures

A

alloy, solution, colloid

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12
Q

element

A

made of one type of atom in particle groups

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13
Q

compound

A
  • made of two or more different types of atoms in each particle group
  • made of two or more elements chemically joined
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14
Q

some useful mixtures

A

ores, saline solution

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15
Q

ores

A

rocks which contain a high enough content of a metal to make extraction of the metal profitable
- hematite –> iron oxide –> iron
- bauxite –> aluminium oxide –> aluminium

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16
Q

percentage of composition of mixture

A

% composition by mass = mass of substance / mass of mixture x 100%

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17
Q

what are separation techniques by particle size?

A
  • sieving
  • filtration
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18
Q

what is sieving?

A

using a metal net, separating the particles from larger particles e.g. gravel from sand

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19
Q

what is filtration?

A

uses a special membrane with fine holes allowing liquids through but not undissolved solids

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20
Q

what are separation techniques by density?

A
  • sedimentation
  • separating by funnel
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21
Q

what is sedimentation?

A

allows time for denser undissolved solids to settle to the bottom of a container

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22
Q

what are separation techniques by boiling point?

A
  • evaporation
  • distillation
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23
Q

what is evaporation?

A

uses heat to boil off the liquid part of a solution, leaving the solute behind

24
Q

what is distillation

A

is evaporation with an added stepp to capture and condense the boiled liquid in a second chamber

25
Q

what are elements made of?

A

made of one atom in each particle group

26
Q

what is a molecule?

A

A molecule is two or more atoms connected by chemical bonds, which form the smallest unit of a substance that retains the composition and properties of that substance

27
Q

what is a lattice?

A

a regularly repeating arrangement of atoms in three dimensions

28
Q

how can you classify elements?

A
  • physical properties
  • chemical properties
29
Q

what physical properties can elements be classified by?

A
  • lustre
  • melting & boiling point
  • malleability
  • ductility
  • electrical conductivity
  • heat conductivity
  • density
30
Q

what chemical properties can elements be classified by?

A
  • ability to react with acid
  • the ability to react with oxygen in the air
  • ability to react with water
31
Q

what is an atom?

A
  • the smallest particle matter that exists by itself in nature
  • the smallest unit of an element that has all the properties of that element
32
Q

what is the basic structure of an atom?

A

made of three subatomic particles, proton, neutron and electron
- proton = + charge
- neutron = neutral charge
- electron = - charge
in the core protons and neutrons are grouped together, and electrons move around the nucleus at high speed in an electron configuration

33
Q

what are isotopes?

A

atoms of the same element can have a different number of neutrons

34
Q

what does the bohr model of the atom tell us?

A
  • electrons can only move with a fixed amount of energy
  • electrons with the same energy level move in the same orbit
  • orbits closer to the nucleus contains lower energy
  • each energy level has a max. no. of electrons
35
Q

mass of atom = ?

A

= mass of protons + mass of neutrons

36
Q

avg. atomic mass?

A

mass no. + mass no. / amount of elements

37
Q

what is periodicity?

A

refers to the pattern of similar properties recurring at intervals when examining elements in increasing atomic number

38
Q

what are the trends in electron configuration?

A
  • elements in the same group have similar electron configurations
  • more energy down a group
  • different sub-shells are filled going across a period
39
Q

what is the core charge of an atom?

A

core charge = no. of protons - no. of electrons in inner shell

40
Q

what are the trends in atomic radius?

A
  • decreases across the period because core charge increases and pulls each valence electron closer to the nucleus
    increases down a group because the effect of the core charge is reduced
41
Q

what is ionisation energy?

A

refers to the amount of energy required to dislodge an electron from an energy shell of a gaseous atom

42
Q

what are trends for ionisation energy?

A

increases across a period and decreases down a row

increases across - increase in core charge
decreases down - electron is further from the nucleus so less tightly held

43
Q

what is electronegativity?

A

is the ability of an atom to attract an electron into its valence shell

44
Q

what are trends of electronegativity?

A

increases as you move from left to right across a period and decreases as you move down a group.

45
Q

what are the trends in reactivity with water?

A

Down a group the reactivity of metals increases because it is easier for a metal atom with greater number of shells to lose electrons. Across a group the reactivity of metals decreases because the increasing core charge makes it more difficult for a metal atom to lose electrons.

46
Q

what does melting point & boiling point indicate?

A

indicators of the strength of the bonding between particles or particle groups in a substance

46
Q

what is ionic bonding

A
  • An ionic bond is a type of chemical bonding that occurs between a cation and an anion.
  • To form ions, which are charged particles, there is a transfer of electrons.
  • It results in one atom positive and the other negative.
47
Q

what is covalent bonding

A
  • Covalent bonding occurs when two non-metal atoms share electron to gain a full outer shell which will make the atom achieve a stable electron configuration.
  • There can be single, double or triple bonds.
48
Q

electronegativity and bonding

A
  • polar covalent bond, difference in electronegativity of 1.0 - 1.7, which is where they share electron unequally
  • ionic bond, difference in electronegativity >1.7, the atom takes the electrons
  • non-polar covalent bond similar electronegativity, this is when electrons are shared
49
Q

what are the shapes of molecules useful for?

A

Molecular shapes are crucial for understanding covalent molecular substances’ properties like melting point, boiling point, hardness, and solubility, as they determine how molecules interact

50
Q

what is the VSEPR model?

A

Valence Shell Electron Pair Repulsion Theory is used to determine the shape of small molecules.

51
Q

what are non-polar molecules?

A
  • A non-polar molecule is a molecule that does not have electrons due at just one end of the molecule.
  • The electrons are spread out evenly making it an even distribution of charges and neutral overall.
52
Q

what are polar molecules?

A
  • A polar molecule is when one end of the molecule is slightly positive and the at the other end is slightly negative.
  • A polar molecule is still neutral overall but has an uneven distribution of charges
53
Q

what is a dispersion force?

A

Dispersion forces are attractions between non-polar molecules due to temporary dipoles caused by electron movement. They’re weak but always present, and strengthen with larger molecule size because more electrons can create temporary dipoles.

54
Q

what are dipole-dipole forces?

A

Dipole-dipole forces occur in polar molecules due to attraction between positive and negative ends. They’re weak because partial charges are small but permanent.

55
Q

what is hydrogen bonding?

A

Hydrogen bonding is a special type of dipole-dipole attraction between molecules, not a covalent bond to a hydrogen atom. It results from the attractive force between a hydrogen atom covalently bonded to a very electronegative atom such as a N, O, or F atom and another very electronegative atom.

chemistry (5 decks)

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