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Chemistry > Topic 1.1 - Stoichiometric Relationships > Flashcards

Topic 1.1 - Stoichiometric Relationships Flashcards

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1
Q

Define an atom

A

the smallest particle of a chemical element

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2
Q

Define an element

A

a pure substance containing only one kind of atom, that cannot be broken down into other substances

*elements can exist as an atom (monatomic) e.g. noble gases
*elements can exist as molecules (diatomic)
e.g. oxygen, nitrogen

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3
Q

Define a compound

A

a chemical combination of two or more different kinds of elements, containing a fixed ratio of atoms.

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4
Q

Define a molecule

A

a molecule consists of two or more atoms of the same element, or different elements, that are chemically bonded together

  • molecules of an element (same atoms)
  • molecules of a compound (different atoms)
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5
Q

Define a mixture

A

two or more different chemical substances that are not chemically combined

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6
Q

what makes up an atom

A

consists of a nucleus (made up of protons and neutrons), surrounded by electrons

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7
Q

example of a molecule of an element

A

hydrogen - has 2 hydrogen atoms = H2
oxygen - has 2 oxygen atoms = O2

(known as diatomic molecules)

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8
Q

example of a molecule of a compound

A

water - 2H + O
table salt - Na + Cl

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9
Q

describe the properties of a compound

A

the physical and chemical properties of a compound are different from its component elements

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10
Q

example of a mixture

A

air - made up of chemical compounds such as oxygen, nitrogen, carbon dioxide

*substances burn in air because the oxygen present supports combustion

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11
Q

what changes the properties of compounds compared to their component elements

A

the bonding between atoms in compounds changes their properties

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12
Q

NaCl - describe the different properties of its component elements

A

Na + Cl

Na (sodium)
= highly reactive metal that reacts violently with water

Cl (chlorine)
= toxic gas used as a chemical weapon

NaCl (Sodium Chloride)
= white crystalline solid, table salt that we sprinkle on our food

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13
Q

MgO - describe the different properties of its component elements

A

Mg + O

Mg (magnesium)
= silvery, shiny and hard metal
= burns with bright light and underwater
= conducts electricity and heat

O (oxygen)
= colourless gas
= doesn’t conduct heat or electricity

MgO (magnesium oxide)
= doesn’t conducts electricity in a solid state
= conducts electricity in molten state
= soft white powder

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14
Q

what do the subscripts in a compound convey

A

the number/ratio of atoms of each element in a compound

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15
Q

what does a chemical equation show

A

the formation of compounds from elements in a chemical change/reaction

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16
Q

what is the law of conservation of mass

A

in a chemical reaction, mass is neither created nor destroyed

17
Q

what are stoichiometric coefficients

A

the number of units of each term in a chemical equation

18
Q

what happens to the atoms in a chemical reaction

A

the number of atoms of each element remains the same

19
Q

what happens to the properties in a mixture

A

the properties of the component elements stay the same as they were in pure form

20
Q

characteristics of mixtures

A

their composition is not fixed
e.g. air we breathe in contains around 20% of oxygen, whereas the air we breathe out contains around 16% of oxygen

21
Q

what is a homogenous mixture

A

uniform composition and properties throughout (looks the same)

22
Q

what is a heterogenous mixture

A

non-uniform composition and properties are not the same throughout (you can see differences)

23
Q

can you separate a mixture

A

yes, since the components retain their individual properties, they can be separated easily

24
Q

examples of homogenous substances

A

table salt, pure gold, brass metal

25
Q

examples of heterogenous substances

A

iron rust, dirt, concrete, vegetable soup

26
Q

technique to separate sand and salt

A

difference in property of components = solubility in water

technique = solution and filtration

27
Q

technique to separate iron and sulfur

A

difference in property of components =
magnetism

technique = response to magnet

28
Q

how to determine the state of matter

A

states of matter are determined by the temperature and pressure

29
Q

how does H2O change states of matter

A

temperature drops =
liquid water changes into a solid
e.g. ice, hail, snow

temperature rises =
liquid water changes into a gas
e.g. steam

30
Q

what is the difference between states of matter

A

the energies of particles

31
Q

differences between the states of matter

A

solid =
- particles closely packed, has a fixed shape and volume
- inter-particle forces strong and particles vibrate in position

liquid =
- particles more spaced, has no fixed shape but a fixed volume
- inter-particle forces weaker and particles can slide over each other

gas =
- particles spread out, has no fixed shape or volume
- inter-particle forces negligible and particles move freely

32
Q

what is the kinetic theory of matter

A

the average kinetic energy of particles is directly related to the temperature.

33
Q

how is the state of matter determined

A

strength of forces between particles which is known as inter-particle forces

34
Q

how is temperature and kinetic energy related

A

Temperature is a measure of the average kinetic energy of particles in a substance. Increasing temperature leads to an increase in the kinetic energy of particles

35
Q

In what states does diffusion occur in

A

liquids and gases, because they are fluids and particles can become evenly distributed

36
Q

how does matter change states

A

as the kinetic energy of particles increases with temperature, they will overcome the inter-particle forces and change state

37
Q

What is sublimation

A
38
Q

what is deposition

A
39
Q

how is a state of matter determined

A

temperature - higher temperature = stronger inter-particle forces

Chemistry (12 decks)

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