The Chemical Earth 8.2

1. the living and non-living components of the earth contain mixtures identify the difference between elements, compounds and mixtures

Elements: are pure substances which only contain one type of atom
Compounds: pure substances consisting of two or more different atoms chemically bonded in a fixed ratio
Mixtures: impure substances consisting of different elements or compounds mixed together with no fixed ratio

Homogenous: same composition throughout elements and compounds are homogenous mixtures can also be homogenous e.g. wine

Heterogeneous: not the same composition throughout e.g. muddy water mixtures can be heterogeneous

Matter is anything that has mass and occupies for example gas, liquid or solids

Solids: particles are packed closely together and vibrate against each other. The particles are not free to move and have a fixed shape.
Liquids: particles are close together, but are free to move therefore have no fixed shape
Gas: particles are far apart from each other and distribute themselves throughout whatever they are contained in.

Construct word and balanced formulae equations of chemical reactions as they are encountered

In an equation there must be equal numbers of each type of atom on either side of the arrow.

NaOH + HCl  NaCl + H²O
1 sodium atom on each side
1 oxygen atom on each side
2 hydrogen atoms on each side
1 chlorine atom on each side
EQAUTION BALANCED

2LiOH + H2SO4  LisSO4 + 2H2O

Asses separation techniques and identify the differences in properties

Immiscible liquid: not mixable e.g. oil and water

EXPERIMENT: Seperating salt and sand
Using the separation technique of evaporation salt and sand were separated. Water was added to the mixture to dissolve the salt. This was then filtered into a conical flask so the sand was separated and only the salt solution was remaining. The salt solution was evaporated in a conical flask over a Bunsen burner, causing salt crystals to be formed.

Describe situations in which gravimetric analysis supplies useful data for chemists and other scientists

Gravemetric analysis: the process of determining the % by mass of one substance in a mixture

It is used to determine whether mining is economically feasible, to determine the composition of compounds in soil to determine weather the soil is appropriate for growing certain crops, to determine the percentage of particular pollutants in water

Identify theat the biosphere, lithosphere, hydrosphere and atmosphere contain examples of mixtures elements and compounds

Atmosphere: is a mixture of gases. (Elements: nitrogen, oxygen, argon. compounds: water, carbon dioxide, nitrogen dioxide etc.)
Hydrosphere: consists of different mixtures (largely water which has dissolved in small amounts ot the elements oxygen, nitrogen, and compound carbon dioxide, sodium, calcium and magnesium sulfates)
Lithosphere: diverse range of mixtures
Biosphere: is the part of earth in which living organisms live. All living things on earth are composed of compounds based on the element carbon.

2. Although elements are found in combinations on Earth, some are found uncombined
Explain the relationship between the reactivity of an element and the likelihood of its existing as an uncombined element.

Noble gases exist as single atoms- they do not react with anything. This is because they have full outer shell of electrons
All alkaline metals react as they only have one electron in their outer shell.
The amount if electrons in the outer shell of an atom determine how they will react.

Classify element as metals, non metals and semi metals according to their physical properties.

Metal properties: usually solids are lustrous, good conductors of electricity and heat, malleable and ductile.
Non metals are metals which do not have these properties
Semi metals are elements which have properties in between metals and non