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year 8 science > chemistry > Flashcards

chemistry Flashcards

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1
Q

what are the three subatomic particles of atoms?

A

protons, neutrons and electrons

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2
Q

what is the charge and location of protons?

A

they are positive and are located in the nucleus

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3
Q

what is the charge and location of neutrons?

A

they are neutral and are located in the nucleus

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4
Q

what is the charge and location of electrons?

A

they are negative and orbit the nucleus

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5
Q

why can electrons be easily lost or transferred during chemical reactions?

A

electrons can be easily lost or transferred from one atom to another during chemical reactions because they are located far from the nucleus.

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6
Q

what do all atoms all seek to be?

A

atoms seek to be neutral (no. protons = no. electrons).

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7
Q

what is the electron shell?

A

the electrons’ orbital path around the atom’s nucleus.

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8
Q

what are atoms?

A

basic particles of chemical elements, containing protons, neutrons and electrons.

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9
Q

what does subatomic mean?

A

smaller than or occurring within an atom. e.g. protons, neutrons and electrons.

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10
Q

what are particles?

A

a relatively small part of something (matter).

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11
Q

what is matter?

A

something that has mass and volume.

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12
Q

what are mixtures?

A
  • when two or more substances mix with each other without participating in a chemical change (but are mixed physically), so that each substance retains its original properties and doesn’t create a new substance. - mixtures can be separated into their components, without a chemical reaction.
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13
Q

examples of mixtures (components)?

A
  • air- mixture of various gases such as nitrogen, oxygen, carbon dioxide, argon, etc.
  • blood- mixture of red blood cells, white blood cells, plasma and platelets.
  • milk- emulsion (mixture) of water, fats, proteins, and sugars.
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14
Q

what are compounds?

A
  • two or more different elements chemically bonded in a fixed ratio.
  • when the elements come together, they react with each other and form chemical bonds that are difficult to break.
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15
Q

examples of compounds (components, chemical formula)?

A

water (H₂O)- compound of 2 hydrogen and 1 oxygen atom.
sodium chloride (NaCl)- compound of 1 sodium and 1 chlorine atom.
carbon dioxide (CO₂)- compound of 1 carbon dioxide and 2 oxygen atoms.

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16
Q

what are molecules?

A

two or more elements (same or different) chemically bonded while still retaining the composition and properties of each substance.

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17
Q

examples of molecules (components, chemical formula)?

A
  • oxygen (O₂)- molecule of 2 oxygen atoms.
  • hydrogen (H₂)- molecule of 2 hydrogen atoms.
  • nitrogen (N₂)- molecule of 2 nitrogen atoms.
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18
Q

contrast mixtures, compounds and molecules?

A
  • the components of mixtures are physically mixed together without participating in a chemical change and can easily be separated into their different components, unlike molecules and compounds which are chemically bonded and are difficult to separate.
  • compounds are two or more different elements chemically bonded in a fixed ratio while molecules are two or more elements (different or same) chemically bonded. Hence, all compounds are molecules but all molecules aren’t compounds.
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19
Q

what are some indications that a physical change has occurred?

A
  • change of shape
  • change in density
  • change of state
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20
Q

what are some features of a physical change?

A
  • involves a change in state, shape or physical composition.
  • can be reversed by physical means.
  • does not form a new substance.
  • does not involve the breaking or forming of chemical bonds between atoms.
  • substances keep their physical and chemical properties.
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21
Q

examples of physical change?

A

evaporation of water, melting an ice cube, mixing ingredients.

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22
Q

what are some indications that a chemical change has occurred?

A
  • colour changes
  • bubble given off
  • gas given off
  • change in temperature
  • precipitate forms (insoluble substance)
  • energy given off (heat, sound)
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23
Q

what are some features of a chemical change?

A
  • involves a change in chemical composition.
  • can only be reversed by chemical means.
  • does form new substances.
  • involves the breaking and forming of chemical bonds between atoms.
  • the physical and chemical properties of the new substances are different to those of the reacting substances.
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24
Q

examples of chemical change?

A

burning toast, rusting, burning wood.

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25
Q

what are chemical reactions?

A

processes where substances interact to form new substances with different properties by breaking and forming chemical bonds (chemical change).

26
Q

what are products?

A

the substances that react with each other

27
Q

what are reactants?

A

the new substances formed by a reaction

28
Q

what are elements?

A
  • a chemical element is a chemical substance that cannot be broken down into other substances by chemical reactions.
  • it is a pure substance and is composed of a certain type of atom (with a certain no. protons, neutrons and electrons)
  • it may come in different forms (state of matter).
29
Q

in what ways do atoms on earth exist?

A
  • as single atoms/monatomic (1 atom). e.g. helium.
  • in clusters of atoms called molecules or compounds (2+ atoms). e.g. oxygen.
  • in large grid-like structures called lattices (countless atoms). e.g. iron.
30
Q

how are elements named?

A
  • a capital letter (e.g. H = hydrogen) or
  • a capital letter followed by a lowercase letter (e.g. Na = sodium)
31
Q

by what characteristics are elements distinguished?

A
  • colour
  • hardness and brittleness
  • melting and boiling points
  • density
  • state
  • reaction with acids and other chemicals
32
Q

what is the periodic table?

A

a systematic way of arranging chemical elements based on their atomic structure and properties.

33
Q

how are elements ordered in the periodic table?

A

elements in the periodic table are ordered by their atomic number (no. protons), whole numbers relating to the internal structure of atoms. Atomic numbers increase from left to right along each row.

34
Q

where are metals, metalloids and non-metals arranged on the periodic table?

A

the majority of the elements are metals, found on the left-middle side of the periodic table, with metalloids separating the metals and the non-metals on the right side of the periodic table (with the exception of hydrogen).

35
Q

what are periods and what do their numbers mean?

A

periods are rows in the periodic table. The period number represents the number of electron shells the elements have. There are 7 periods.

36
Q

what are groups and what do their numbers mean?

A

groups are columns in the periodic table. Elements in the same group have the same number of valence electrons (no. electrons in the outer shell), which affects their properties.

37
Q

what is the first element, symbol, state at room temperature and is it a metal, metalloid or non-metal?

A

hydrogen, H, gas, non-metal

38
Q

what is the second element, symbol, state at room temperature and is it a metal, metalloid or non-metal?

A

helium, He, gas, non-metal

39
Q

what is the third element, symbol, state at room temperature and is it a metal, metalloid or non-metal?

A

lithium, Li, solid, metal

40
Q

what is the fourth element, symbol, state at room temperature and is it a metal, metalloid or non-metal?

A

beryllium, Be, solid, metal

41
Q

what is the fifth element, symbol, state at room temperature and is it a metal, metalloid or non-metal?

A

boron, B, solid, metalloid

42
Q

what is the sixth element, symbol, state at room temperature and is it a metal, metalloid or non-metal?

A

carbon, C, solid, non-metal

43
Q

what is the seventh element, symbol, state at room temperature and is it a metal, metalloid or non-metal?

A

nitrogen, N, gas, non-metal

44
Q

what is the eight element, symbol, state at room temperature and is it a metal, metalloid or non-metal?

A

oxygen, O, gas, non-metal

45
Q

what is the ninth element, symbol, state at room temperature and is it a metal, metalloid or non-metal?

A

fluoride, F, gas, non-metal

46
Q

what is the tenth element, symbol, state at room temperature and is it a metal, metalloid or non-metal?

A

neon, Ne, gas, non-metal

47
Q

what is the eleventh element, symbol, state at room temperature and is it a metal, metalloid or non-metal?

A

sodium, Na, solid, metal

48
Q

what is the twelfth element, symbol, state at room temperature and is it a metal, metalloid or non-metal?

A

magnesium, Mg, solid, metal

49
Q

what is the thirteenth element, symbol, state at room temperature and is it a metal, metalloid or non-metal?

A

aluminium, Al, solid, metal

50
Q

what is the fourteenth element, symbol, state at room temperature and is it a metal, metalloid or non-metal?

A

silicon, Si, solid, metalloid

51
Q

what is the fifteenth element, symbol, state at room temperature and is it a metal, metalloid or non-metal?

A

phosphorus, P, solid, metal

52
Q

what is the sixteenth element, symbol, state at room temperature and is it a metal, metalloid or non-metal?

A

sulphur, S, gas, non-metal

53
Q

what is the seventeenth element, symbol, state at room temperature and is it a metal, metalloid or non-metal?

A

chlorine, Cl, gas, non-metal

54
Q

what is the eighteenth element, symbol, state at room temperature and is it a metal, metalloid or non-metal?

A

argon, Ar, gas, non-metal

55
Q

what is the nineteenth element, symbol, state at room temperature and is it a metal, metalloid or non-metal?

A

potassium, K, solid, metal

56
Q

what is the twentieth element, symbol, state at room temperature and is it a metal, metalloid or non-metal?

A

calcium, Ca, solid, metal

57
Q

example of metals?

A

gold, silver, aluminium, copper, iron

58
Q

examples of metalloids?

A

boron, silicon, germanium, arsenic, antimony, tellurium

59
Q

examples of non-metals?

A

hydrogen, helium, iodine, argon, oxygen, neon, nitrogen, carbon

60
Q

what are common features of metals?

A
  • has a high melting point
  • good conductors of electricity and heat
  • solid at room temperature (exception: mercury)
  • malleable (able to be bent into sheets)
  • ductile (able to be stretched into wires)
  • are silver/grey (exception: gold, copper)
  • has a metallic lustre (exception: lead, sodium)
  • some metals are magnetic
61
Q

what are metalloids?

A

elements that have both features of metals and non-metals

62
Q

what are common features of non-metals?

A
  • not/opposite of a metal
  • not good conductors of electricity and heat
  • all elements that are gases at room temperature are non-metals
  • not malleable (able to be bent into sheets)
  • not ductile (able to be stretched into wires)
  • are not silver/grey
  • does not have a metallic lustre
  • are not magnetic

year 8 science (6 decks)

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