chemical bonding - topic 2 test revision Flashcards

1
Q

what are the 3 different types of chemical bonding

A
  • ionic
  • covalent
  • metallic
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2
Q

different physical properties

A
  • density (how much matter/unit volume)
  • colour and surface texture
  • conductivity (heat & electricity)
  • state (liquid, solid, gas, ect.)
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3
Q

Define a chemical bond

A

A mutual attraction between two atoms resulting from a redistribution of their outer electrons. This results in a stable formation of atoms and provides the resulting compound with a unique set of properties.

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4
Q

what structure are ionic compounds formed in

A

lattice structure

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5
Q

what is ionic bonding

A
  • the force of attraction between a cation (pos) and an anion (neg)
  • held together through electrostatic attraction
  • results in the transfer of electrons from one of the bonding atoms to the other to produce a full outer shell on each atom
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6
Q

what are the properties of an ionic compound and explain each of them

A
  • high melting point; has high melting point because it has strong ionic bonds throughout the 3d lattice and needs large amounts of energy to break those bonds
  • Strong; has strong structure because it has high ionic bonds throughout the lattice
  • Brittle; it is brittle because if a certain amount of force is applied it can cause disruption to the lattice. Like ions will repel and the lattice can shatter
  • conduct electricity but only in their molten or dissolved state; because there are charged particles that are are ions that move freely
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7
Q

define dissolved

A

solute breaks up into very small particles surrounded by h20 molecules

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8
Q

define soluble

A

salt that dissolves in water (soluble salt)

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9
Q

define solvent

A

substance that does the dissolving

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10
Q

define solute

A

substance that is dissolved in another substance

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11
Q

define saturated

A

when no more solute can dissolve

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12
Q

define crytallized

A

when the solute comes out of solution and small solid crystals form

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13
Q

define solubility

A

amount of solute that dissolves in a given volume/mass of solvent at a given temperature (35g/100g h20 at 25 degrees)

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14
Q

what is a solubility curve

A

the standard measure of solubility of a substage at a given temperature is how many grams dissolve in each 100g of solvent to form a saturated solution. this graph shows the results of performing these tests at different temps

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15
Q

what is a saturated solution

A

saturated solution; contains maximum amount of solute for the volume of a solution at a particular temperature
(on the curve)

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16
Q

what is an unsaturated solution

A

unsaturated solution: contains less than maximum amount of solute in the solvent
(below the curve)

17
Q

what is a supersaturate solution

A

a solution that contains more solute than it should at that temperature. this can be achieved by slowly cooling a saturated solution
(above the curve)

18
Q

what are covalent compounds

A

covalent compounds are formed from two non-metal atoms. as these atoms come closer their outer electrons are attracted to the nucleus of both atoms and the electrons become shared by the atoms. these shared electrons count towards the shells of both atoms and therefore help fill up incomplete electron shells

19
Q

describe covalent bonds

A

they are held together by the two shared electrons. a pair of electrons shared like this is known as a covalent bond. these shared electrons makes the outer shell of each atom full

20
Q

how do multiple bonds work

A

mostly electrons are shared in pairs. there are some compounds where they share in fours or even sixes. this make single, double and triple bonds.

21
Q

what are the two ways to show covalent bonds through diagrams

A
  • Lewis Structure / Dot diagram
  • Valence Structure
22
Q

what is the lewis diagram

A

the lewis diagram is where electrons pairs are shown evenly around the nucleus.

23
Q

what is the valence structure

A

this represents the bonding pairs through a straight line

24
Q

what does an intermolecular bond do

A

it is the bond that connects the two covalent bonded atoms

25
Q

what is a discrete covalent bond

A

the discrete covalent bond is the substances that are made up of individual molecules held together by weak forces. the covalent bonds holding the two atoms are very strong but the forces holding the molecules together are very weak

26
Q

what are the properties of a discrete covalent bond and explain them

A

soft; discrete molecules are held together by weak forces between each molecule. this means that the bonds are easy to break and hence the substance is soft
low mpt and bpt; the weak forces between molecules can be broken easily with low temps. therefore the mpt and bpt are low
doesn’t conduct electricity; no free charged particle. the electrons are still held strongly within each molecule (covalent)

27
Q

how do you name discrete covalent bonds

A

use the prefixes before each cation or anion depending on how many atoms of each substance there are. don’t use 1 or mono for the first word

28
Q

what are different prefixes

A

mono - 1
di - 2
tri - 3
tetra - 4
penta - 5
hexa - 6
hepta - 7
octa - 8
nona - 9
deca - 10

29
Q

what are the different shapes of covalent molecules

A

linear
v-shaped
pyramidal
tetrahedral

30
Q

when do those shapes occur

A
  • linear; 1 bonding and 3 non-bonding
  • v-shaped; 2 bonding and 2 non-bonding
  • pyramidal; 3 bonding 1 non-bonding
  • tetrahedral; 4 bonding
31
Q

what is a covalent lattice

A

these are lattices with all the bonds being covalent meaning it is really strong and often seen as crystals like diamond. not made of molecules. there is also no free electrons so they cannot conduct electricity

32
Q

what is a covalent layer lattice

A

these have strong covalent bonds between atoms within a 2D layer and then held together by weaker forces or dispersion forces between each layer. free electrons so it can conduct electricity. best example is a pencil (graphite)

33
Q

what is the difference between graphite and diamond

A

diamond is a covalent lattice and graphite is a covalent layer lattice. this means diamond is stronger because all the bonds holding the atoms together are strong covalent bonds meaning it is harder to break. and graphite is a covalent layer lattice meaning that there is weaker bonds holding together layers of covalent bonds