Structure 1.1 Introduction to the particulate nature of matter

native form

uncombined with other elements in nature

why can a homogeneous mixture be formed?

the inter-particle attraction within the different components have to be similar to those between the components in the mixture

solution

A homogeneous mixture of two or more substances

how does matter change state?

the kinetic energy will overcome the inter-particle forces

Maxwell-Boltzmann distribution

The distribution of energies (and therefore speeds) of the molecules in a gas or liquid.

How can matter be classified?

pure substances and mixtures

how can oure substances be classified?

elements and compounds

how can mixtures be classified?

heterogeneous and homogeneous mixtures

element

a pure chemical substance composed of atoms with the same number of protons in the atomic nucleus

atom

the smallest particle of an element to show the charasteristic properties of that element

what gives an atoms its charasteristic properties?

the distinct number of protons and electrons

chemical symbol

A one or two letter representation of an element (specific)

chemical compound

two or more elements (atoms) chemically combined in a fixed ratio

do the physical and chemical properties of elements change in a compound?

yes

do the physical and chemical properties of elements change in a mixture?

no

chemical formula

A combination of chemical symbols and numbers to represent a substance

mixture

A combination of two or more substances that are not chemically combined, no fixed ratio of elements/compounds

Why is air considered a mixture?

the separate components are interspersed with each other but not chemically bonded

do mixtures have chemical formuals?

no, as they have no fixed ratios

how can the component of a mixture be separated?

(physical) separation methods

homogeneous mixture

a mixture with unifrom composition and properties throughout

heterogeneous mixture

a mixture with non-uniform composition and no uniform properties throughout

why are heterogeneous mixtures formed?

the interactions between the components are different (for example water, polar and oil, non-polar)

why can the components of mixtures be separated?

a distinct physical property (a difference like solubility, boiling point, magnetism etc.)

filtration

a process that separates a solid from a liquid or gas by using a memebrane (like a filter paper)

residue

Solid left in the membrane after filtration

filtrate

liquid (or gas) that has passed through a membrane(filter) with its solutes

Solvation

the process by which the positive and negative ions of an ionic solid become surrounded by solvent molecules (dissolved), water molecules surround the ions

how can solvation be used as a part of filtration

as one of the components dissolves into the solvent the other component does not (based on solubility) and thus the two components can be separated by filtration

evaporation (separation technique)

separates solute from solvent in a solution. (separation technique) due to different boiling points

crystallization

a separation technique that results in the formation of pure solid particles of a substance from a solution containing the dissolved substance (salt crystals froming from a salt solution after evaporation)

distillation

a process that separates a solvent from a solute based on their distinct boiling points

How does distillation work?

the solvent has a lower boiling point and thus when the solution is heated the solvent evaporates into a gas which travels into the condensation tube where it is condensed back into a liquid

paper chromatography

method of separating a mixture of different colours. The liquid soaks through the paper and carries the mixture with it. Some substances are carried faster than others so the substances are separated along the paper

why are some subtances carried up more than others in paper chromatography?

different affinites for water (also about solubilty)

Kinetic Molecular Theory

a model to explain physical properties of matter and changes in state

do the chemical properties of a substance change when the state of matter changes?

no, because the change in state only affects the physical properties of the substace and not the chemical ones

what determines the state of matter that a substance exists in?

temperature and pressure

states of matter

the physical forms of matter, which include solid, liquid, and gas

how does increasing temperature affect particles?

the kinetic energy of them increase as the temperature in creases and vice versa

physical characteristics of the solid state of matter (4)

particles closely packed, partciles vibrate in position, fiex shape, fixed volume

why do particled vibrate in position in the solid state of matter

strong inter-particle forces

physical characteristics of the liquid state of matter (4)

particles more spaced, particles can slide past each other, no fixed shape, fixed volume

why do particles slide past each others in the liquid state of matter

weaker inter-particle forces

the physical characteristics of the gaseous state of matter

particles fully spread out, particles move freely, no fixed shape, no fixed volume

why can particles move freely in the gaseous state of matter?

negligble inter-particle forces

why is it called the kinetic molecular theory?

the average kinetic energy is particles is directly related to the temperature and pressure in a system and the strenght of inter-particle forces is relative to the average kinetic energy

when is a substance in a solid state of matter?

when the inter-particle forces are stronger than the kinetic energy of them

fluid

A substance that flows

why are liquids and gases called fluids?

Because they flow

diffusion

The process of spread of a feature or trend from one place to another over time, particles spread out more evenly

kinetic energy

energy associated with motion/movement

How is kinetic energy dtermined?

mass, speed/velocity of a sub stance

is the average kinetic energy the same across different in different subtsances at the same temperature and pressure?

yes

what kind of partciles diffuse the fastest and why?

smaller particles as there is an inverse relationshio between mass and velocity (kinetic energy formula)

state symbols

solid (s), liquid (l), gas (g), and aqueous solution (aq)

aqueous solution

a solution in which water is the solvent

solute

A substance that is dissolved in a solution., the less abundant component, any state of matter

solvent

the substance in which the solute dissolves, the more abundant component, usually liquid

melting point/freezing pint

The temperature at which a solid becomes a liquid, specific for each substance at a fixed temperature and pressure

boiling point/condensation point

The temperature at which a liquid changes to a gas, specific for each substance at a fixed temperature and pressure

how can matter change states reversibly?

changing the temperature

how is the reversibility of the the changes in state represented in equations?

a reversible arrow (two arrows pointing if different directions)

sublimation

A change directly from the solid to the gaseous state without becoming liquid (a direct inter-conversion)

deposition

the reverse of sublimation (gas to solid)

melting

solid to liquid

freezing

liquid to solid

vaporization (evaporation/boiling)

Liquid to gas

condensation

Gas to liquid

the difference between evaporation and boiling (2 things)

boiling only happens at a fixed temperature ( and pressure) whereas evaporation happens at all temperatures below the boiling point, evaporation only happens from the surface whereas boiling happens from throughout the liquid

when does a liquid boil

when vapor pressure equals atmospheric pressure, the vapour from evaporation increases with the temperature

why does a lower pressure enable liquids to boil at a lower temperature

a lower external pressure needs less vapour to be released in order to macth the pressure

why are pressure cookers used?

a higher external pressure needs a higher vapour pressure and thus the boiling point increases furthermore decreasing the cooking time as something can be cooked at a higher temperature

dew point

The temperature at which condensation begins, depends rom atmospheric pressure

heat curve

A graph that demonstrates the changing of the states of a substance by plotting temperature vs energy input

what happens when a solid is heated

the vibrational energy of the particles increases and thus the temperature increases

what happens at a melting point?

vibrations have enough energy for the particles to start moving more freely, sloid to liquid

why is the temperature constant at a melting point even though more energy in added?

the energy goes into breaking the inter-particle forces but not to rais ethe kinetic energy of the particles

what happens when a liquid is heated?

the partciles gain more kinetic energy

what happens at the boiling point?

The particles have enough energy to break their bonds and the liquid becomes a gas, bubbles and gas forming throughout the liquid

why does the boiling point require more energy than the melting point?

all of the inter-particle forces need to be broken and not just some of them

what happens when a gas is heated?

the kinetic energy of the partciles increase with temperature, in a closed system also the pressure increases

endothermic

Absorbs heat(energy)

exothermic

Releases heat(energy)

which of the changes in state are endothermic processes?

melting and boiling as separating particles and bonds between them requires energy

which of the changes in state are exothermic processes?

freezing, condensation as inter-particle forces bring the particles closer together and there's less kinetic energy

absolute zero

The coldest temperature, 0 Kelvin (-273 celcius), that can be reached. It is the hypothetical temperature at which all molecular motion stops.

SI unit for temperature

Kelvin (K)

the conversion from celcius to kelvin

K = C + 273.15 (one degree is the same amount of change in temperature in each scale)

what does the total kinetic energy include

temperature, and particle collisions where the kinteic energy of them changes a bit