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Grade 7 Science > Matter, Molecules and More! > Flashcards

Matter, Molecules and More! Flashcards

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1
Q

What is a mixture?

A
  • combination of substances which are not chemically joined together
  • mixtures have the same properties as their components
  • components can be separated from the mixture
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2
Q

Give an example of a mixture

A
  • sugar and salt

- air with nitrogen, oxygen

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3
Q

What is Homogeneous?

A

composed of parts of elements that are all of the same kind

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4
Q

Example of homogeneous

A

marshmallows, honey and material having only one set of properties

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5
Q

Example of heterogeneous

A

when something is made of different parts

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6
Q

Example of heterogeneous

A

sand and mixtures made up of parts that retain their own properties, even if these properties are not visible to the unaided eye

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7
Q

What is a solution?

A
  • mixture in which other substances are dissolved
  • components of a solution may not be separated from the solution by leaving it to stand or by filtration. If a material dissolves in a liquid, the material is said to be soluble
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8
Q

example of solution

A

salt in sea water

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9
Q

what is a suspension

A

a mix of liquids with particles of a solid which may not dissolve in the liquid
- the solid may be separated from the liquid by leaving it to stand or by filtration

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10
Q

example of suspension

A

sand in water

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11
Q

Matter can be separated into these 3 categories

A

solid, liquid, gas

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12
Q

how do you describe matter

A

properties

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13
Q

define matter

A

anything that takes up space, has mass, and is made up of particles

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14
Q

what makes solutes dissolve better

A

1) agitation (stirring, shaking)
2) temperature (heat makes solute dissolve in liquid faster, cold makes gas dissolve in a liquid faster)
3) size (less solute, quicker it will go

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15
Q

what is a universal solvent?

A

water

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16
Q

why is water a good universal solvent?

A
  • solutes dissolve well in it
  • it’s polarized (clings to things)
  • has a negative and positive charge
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17
Q

what is an ionic bond?

A

atoms have positive or negative charges. id a neg meets a positive, their opposite charges attract and glue them together

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18
Q

what is a covalent bond?

A

a chemical bond formed by sharing one or more electrons between atoms

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19
Q

what is concentrate?

A

when they have more of the base component (solvent) removed example: when you remove water from fruit juice

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20
Q

what is capillary action?

A

physical effect caused by the interaction of a liquid with the walls of a thin tube

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21
Q

what is a pure substance?

A

elements

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22
Q

what is a physical change?

A

does not affect the molecules inside something, it only changes its shape

  • change size or colour
  • it only chnages the state of matter
  • no new material formed
  • can occur by increasing or decreasing the temp
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23
Q

what is a chemical change?

A
  • can change the chemicals of something

- example: burn paper, then it’s changed because there are no more molecules

24
Q

what are signs of chemical reaction?

A
  • formation of bubbles
  • colour change
  • production of heat or light
  • formation of a solid
  • baking is a chemical reaction
25
Q

what is a saturated solution?

A
  • means you want to dissolve a solid into a liquid, but there’s too much of a solid, so not all can dissolve
  • must be at a certain temp
  • heat it up to make is supersaturated
26
Q

what is matter made up of?

A

tiny particles called atoms and molecules

27
Q

particles of matter

A

1) in constant motion

2) held together by very strong electric forces

28
Q

what affects the speed of particles between matter?

A

higher the temp, the faster the speed of the molecules

29
Q

what does the particle theory of matter explain?

A
  1. pure substances are homogeneous
  2. physical changes (melting, evaporation, sublimation, dissolving)
  3. characteristic physical properties - density, viscosity, electreical and thermal conductivity
30
Q

what is hydrophilic

A

loving water

example: sugar is more hydrophilic than salt so it dissolves in water more quickly than salt

31
Q

what is hydrophobic

A

hating water

32
Q

what are colloids

A
  • heterogeneous mix composed of tiny particles suspended in another material
    example: milk
33
Q

why is milk a colloid?

A

particles can be solid tiny droplets of liquid, or tiny bubbles of gas

34
Q

what are dissolved gases

A

gases that have been dissolved into the solvent

example: oxygen and CO2 dissolved into water so fish can live

35
Q

what is dilute?

A
  • weaken the strength of a solution by increasing the amount of solvent
  • make thinner or less concentrated (add water)
  • to lessen the force, strength or purity of a mixture
36
Q

what is the rate of dissolving

A

the speed at which a solute dissolves in a solvent

37
Q

what is solubility

A
  • the ability of a substance to dissolve
38
Q

what is a solute?

A

the substance being dissolved

39
Q

what is a solvent?

A

substance in which the solute is being dissolved

40
Q

what is a solution?

A

a mix of solute and solvent

41
Q

what is an unsaturated solution?

A
  • a solution that can dissolve more solute at a given temperature
  • more of the solute could dissolve at the same temperature
  • if you add more solute to the liquid, it would keep dissolving
42
Q

example of unsaturated solution?

A

a teaspoon of salt in a bucket of water is unsaturated… if you add another teaspoon it would also dissolve

43
Q

what is a supersaturated solution?

A

a solution that contains more of the dissolved material than coudl be dissolved by the solvent under normal circumstances
- heat up a saturated solution

44
Q

what is a soluble? example

A

able to be dissolved; sugar is soluble in water

45
Q

what is insoluble?

A

that cannot be dissolved

46
Q

what is settling?

A
  • the process by which pariticulates settle to the bottom of a liquid and form sediment
  • for gravity settling, this means particles will fall to the bottom of the vessel
47
Q

what is sediment?

A

naturally occurring material tha tis broken down by process of weathering and erosion and is subsequently transported by the action of fluids such as wind, water

48
Q

what is slurry?

A

a thick suspension of solids in a liquid

49
Q

what is a mechanical mixture? examples

A

when two or more diffent materials are mixed together, but are visibly not wholly one
example: sand and stones on a beach, milk in a cereal bowl

50
Q

how to atoms move in gas?

A

fast

51
Q

do atoms in liquid move faster or slower than gas?

A

slower

52
Q

how do atoms move in solids?

A

slowest

53
Q

what is an atom?

A
  • a part or particle considered to be an irreducible constituent of a specified system
  • an extremely small part, quantity or amount
54
Q

do atoms have nuclear energy?

A

yes

55
Q

what is a molecule?

A
  • the smallest particle of a substance that retains the chemical and physical properties of the substance and is composed of two or more atoms
  • a group of the like or different atoms held together by chemical forces
  • a small particle, a tiny bit
56
Q

is there space between molecules?

A

yes. it is a space-time continuum

Grade 7 Science (5 decks)

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