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Chemistry Dot Points- the Chemical Earth

By xalicenguyen Sep 02, 2013 3096 Words
3.1.1 Identify that matter is made of particles that are continuously moving and interacting The particle theory states that all matter is made up of tiny particles and they are constantly moving/continual state of motion. 1.1.2 Identify the difference between elements, compounds and mixtures in terms of particle theory Elements are simplest form substance meaning cannot be decomposed further physically or chemically. They are made up of same type of atoms only e.g. helium, oxygen. Compounds are pure and they consist of 2 or more elements bonded chemically (fixed ratio). They can be decomposed chemically. E.g. sodium chloride, carbon dioxide Mixtures are the blending (physically combined, hence can be separated) of 2 or more pure substances, e.g. sand, mud 1.1.3 Identify that the biosphere, lithosphere, hydrosphere, and atmosphere contain examples of mixtures of elements and compounds Biosphere: where living organisms are found, since most living things are composed of cells therefore they contain complex carbon compounds. E.g. carbohydrates, fats Lithosphere: earth’s crust which contain many types of minerals (mixture sedimented with sand, soil & rock) most abundant compound/mineral is quartz Hydrosphere: ‘hydro’ so water is most abundant compound this leads to oxygen & hydrogen being most abundant elements. E.g. sea water (mixture) contains many dissolved minerals such as salts Atmosphere: layer above earth’s surface which contains mixture of gases. E.g. nitrogen (75.3%) & oxygen (23.1%) being most abundant gases 2.1.1 Explain the relationship between the reactivity of an element and the likelihood of its existing as an un-combined element The more reactive an element is = less chance finding

The less reactive an element is = more chance of finding
There are two types; monatomic (exists with 1 atom) & diatomic (exists as molecule with 2 atoms) Monatomic elements are un-combined in nature because it’s inert e.g. noble gases such as helium Diatomic elements exists as molecules, bonded with another atom from same element such as oxygen, hydrogen

2.1.2 Classify elements as metals, non-metals and semi-metals according to their physical properties These elements can be classified by their physical properties (lustre, conductivity, malleability, ductility) Physical property| Metal| Semi-metal| Non-metal|

Lustre| lustrous| Low lustre| Dull|
Electrical conductivity| Good| Semi-conductors| Poor|
Heat conductivity| Good| Good| Poor|
Malleability| Malleable| Moderately| Brittle|
Ductility| Ductile| Moderately| Not ductile|
Boiling & melting point| High| High, lower than metals| Low |

2.1.3 Account for the uses of metals and non-metals in terms of their physical properties The uses of metals and non-metals will be determined by their physical properties as well as their chemical properties

Metals- e.g. copper is used for electrical circuits (wiring) for its good conductivity of electricity and its low reactivity Non-metals- e.g. neon is used for neon lighting for its low reactivity 5.1.1 Identify differences between physical and chemical properties of elements, compounds and mixtures Since elements are classified into metals, non-metals and semi-metals they have different physical properties. Whereas for their chemical properties it is how they react with other substances. Elements are grouped into categories based on the properties they share. Elements cannot be decomposed any further. Compounds can be broken down through chemical changes to form elements or undergo chemical changes and form simpler compounds; they have different properties from the elements that form it. Mixtures are the combination of two or more substances that aren’t combined chemically. Two or more materials form a mixture if they don’t react to form a compound. Mixtures can be physically and chemically separated. They are classified into homogenous or heterogeneous. 2.2.1 Plan and perform an investigation to examine some physical properties and some uses of a range of common elements to present information about the elements as metals, semi-metals or non-metals Element sample| Lustre | Electrical conductivity| Malleability | Hardness | Al| Shiny| Yes | High | Soft |

Fe| Shiny| Yes | Low | Very hard |
C| Dull| Yes | Low | Soft |
Mg| Shiny| Yes | High | Soft |
S| Dull | No | Very low | Very soft |
Zinc| Shiny| Yes | Medium| Medium |
In conclusion S was a non-metal because it had no metal like properties and C was a semi-metal because it shared both metal and non-metal characteristics. All other elements were metals. 1.1.4 Identify and describe procedures that can be used to separate naturally occurring mixtures of solids of different sizes, solids and liquids, dissolved solids in liquids, liquids, gases. Solids of different sizes| Insoluble solids and liquids| Soluble solids in liquids| Liquids| Gases| Sieving| Decanting| Crystallisation | Fractional distillation| Gas chromatography| Magnetism | Filtration| Evaporation | Separating funnel| | Sedimentation| Centrifugation| Distillation | Paper/column chromatography| | Froth flotation| | | | |

1.1.5 Assess separation techniques for their suitability in separating examples of earth materials, identifying the differences in properties which enable these separations Separation method:| Property used in separation:|

Sieving | Solids of different sizes|
Evaporation | Solubility |
Crystallisation | Solubility |
Distillation | Boiling points (big difference)|
Fractional distillation | Boiling points (small difference)| Decantation (using separating funnel)| Density of immiscible liquids| Sedimentation and decantation | Density of solids|
Magnetism | Solids of different sizes|
Froth flotation | Solids of different sizes |

2.2.3 Process information from secondary sources and use a periodic table to present information about the classification of elements as: - Metals, non-metals and semi-metals
- Solids, liquids and gases at 25°C and normal atmospheric temperature

Metals, non-metals and semi-metals

Solids, liquids and gases at room temperature

1.1.4 Identify and describe procedures that can be used to separate naturally occurring mixtures of: - Solids of different sizes
- Solids and liquids
- Dissolved solids in liquids
- Liquids
- Gases
Separating solids and liquids: There are two methods:
1) Filtration. The solution is passed through a funnel which is lined with filter paper. The liquid is able to pass through but the solid is caught in the filter. 2) Sedimentation and decantation. The solids are allowed to settle to the bottom of the container. Then the liquid is carefully poured off, leaving the solid at the bottom of the container.

Separating dissolved solids in liquids: There are two methods: 1) Evaporating to dryness. This is done when the liquid is of no use and can be disposed of. The solution is heated until all the liquid has evaporated leaving the solid behind. 2) Distillation. This is done when the liquid is desirable. The solution is placed in the apparatus and heated. The liquid evaporates and moves through tubing to another container. On the way the tube is cooled so that the gas is condensed causing it to change back to liquid state before ending up in a secondary container. The solid is left at the bottom of the first beaker. The liquid collected is called the distillate. Separating Liquids: Again there are two methods:

1) Fractional Distillation. The apparatus is slightly different to that of distillation but the process is the same. The apparatus contains a fractionating column which consists of hundreds of glass beads. This arrangement allows for repeated condensations and evaporations, thus the solution is distilled 10-100 times. Liquid with the lowest b.p comes off first 2) Separating Funnel. Use if the liquids are immiscible (i.e. don’t dissolve in each other). The liquids are layered. One is allowed through the funnel and just before it finishes the valve is closed. Thus separating the liquids. Two solids based on solubility: If one substance in a particular mixture is soluble in a certain substance while the other isn’t they can be separated. The solution is added, which dissolves one of the substances, and then one filtration is used to remove the insoluble substance, the remaining filtrate is dried to retrieve the other solid.

Separating Gases: Again two methods:
1) Fractional Distillation. Gases are condensed to liquid state then distil 2) Differences in solubility. Gases are run through a series of “u” shaped tubes each containing a substance that will dissolve a particular gas, thus leaving only the desired gas(es) at the end. 1.1.5 Assess separation techniques for their suitability in separating examples of earth materials, identifying the differences in properties which enable these separations Separation Method| Property used in the separation|

Sieving| Particle size|
Vaporization (Evap. To dryness)| Liquid has lower m.p. than solid| Distillation| Big difference in b.p.|
Fractional Distillation| Small but significant difference in m.p.| Filtration| One solid, one liquid/solution|
Using a separating funnel| Two immiscible liquids |
Adding a solvent then filtration| One substance is soluble in the chosen solvent, while the others aren’t.|

1.1.6 Describe situations in which gravimetric analysis supplies useful data for chemists and other scientists Gravimetric analysis is determining the quantities (mass) of substances present in a sample. It could be presented by mass or by percentage of total mass. There are several reasons as to wanting to know the per cent composition of a mixture: * To decide whether a newly discovered mineral deposit contains sufficiently high percentage of the required compound to make its extraction from that deposit economically viable * To determine the composition of soil in a particular location to see if it is suitable for growing a certain crop *  To determine the amounts of particular substances present in water or air to decide how polluted the samples are * To decide whether a particular commercial mixture has the same percentage composition as a similar mixture being marketed by a rival company

5.1.1 Identify differences between physical and chemical properties of elements, compounds and mixtures | Physical properties| Chemical properties|
Elements | Metal: * Malleable * Ductile * Found as solids (except mercury) * Good conductors of heat and electricity * Lustrous * High density| Metals: * Form positive ions * Form basic oxides * Form ionic chlorides| | Non-metals: * Brittle * Dull * Found as solids, liquids and gases * Good insulators of heat and electricity * Low density| Non-metals: * Form negative ions * Form acidic oxides * Form covalent chlorides| | Semi-metals: * Have properties of both metals and non-metals * Have intermediate density| | Compounds| Ionic compounds: * Formed between metals & non-metals * Solid at room temp. * Soluble * Non-conductors of electricity in solid state * Conductors of electricity when dissolved in solution| Compounds: * Different chemical properties to their elements * Can be decomposed into elements or simpler compounds| | Covalent molecular compounds: * Non-conductors of electricity * Low melting points * Soft & brittle| | | Covalent network compounds: * Are non-conductors in all states * Are insoluble * High melting points * Hard and brittle| | Mixtures| Heterogeneous mixtures: * Not chemically combined * Demonstrate physical properties of pure substances * No uniform structure| Mixtures: * Demonstrate the chemical properties of their pure substances| | Homogenous mixtures: * Not chemically combined * Demonstrate physical properties of pure substances * Uniform structure| |

1.2.4 Identify data sources, gather, process and analyse information from secondary sources to identify the industrial separation processes used on a mixture obtained from the biosphere, lithosphere, hydrosphere or atmosphere and use the edivdence to; identify the properties of the mixture used in its separation, identify the products of separation and their uses, discuss issues associated with wastes from the processes used

Fractional distillation is used to separate the components of crude oil. Crude oil is separated into refinery gas, petrol, naphtha, kerosene, diesel, oils and bitumen. The main property used to separate these components is their boiling points. Modern separation involves piping crude oil through hot furnaces. It is hot at the bottom and cool at the top. The crude oil separates into fractions according to weight and boiling point. The lightest fractions which include petrol and LPG vaporize and rise to the top. Heavier liquids (with higher boiling points) separate lower down. Products retrieved after the separation include:

- Refinery gas: Bottled gas, fuels
- Petrol: Fuel for cars
- Naphtha: Raw materials for chemicals and products (e.g. Plastic) - Diesel: Fuel for cars
- Kerosene: Fuel for aeroplanes
- Bitumen: Road surfacing
- Oils: Lubricants/grease, also fuel for power stations

Issues associated with wastes include:
- Produced waters, drilling muds and drilling cuttings, as well as discharges of storage displacement are the source of regular and long term impacts of the industry on the marine environment and also in local swamps and land based environments. - Air and Water pollution. Many oil refineries produce wastes that if released into the air or water can be detrimental to local ecosystems. Refineries must store these wastes onsite, treat them and dispose of them appropriately. However, on the rare occasion, these wastes leak into the environment causing widespread disaster. 1.2.2 Identify data sources, plan, choose equipment and preform a first-hand investigation to separate the components of a naturally occurring or appropriate mixture such as sand, salt and water. To separate sand, salt and water; filtration to filtrate out the sand. Then perform evaporation or distillation to separate the salt and water (depends if you want to keep the water or not) 1.2.3 Gather first-hand information by carrying out a gravimetric analysis of a mixture to estimate its percentage composition Determine the percentage composition of magnesium in magnesium oxide Mass of Mg = 24.31 Mass of O = 16.00

% Mg in MgO = (mass of Mg)/ (mass of O)*100%
= 60.3%

3.1.3 Describe atoms in terms of mass number and atomic number The mass number = no. of protons + no. of neutrons
Atomic number = no. of protons / no. of electrons
3.1.2 Describe qualitatively the energy levels of electrons in atoms The atom is described as having electrons existing in stable energy levels at different radial distances from the nucleus. These energy levels are known as ‘’electron shells.’’ Electron shells are numbered from the inner parts of the atoms outwards, and the maximum electron population of each shell is determined by the formula 2.2. The outer electron shell is called the valence shell, and the pattern of arrangement of electrons in each shell id referred to as the electron configuration. 3.1.4 Describe the formation of ions in terms of atoms gaining or losing electrons Ions are formed due to the imbalance of protons and electrons. In a neutrally charged atom, the number of protons equals the number of electrons. When an atom loses electrons, it becomes positively charged as there are more protons than electrons (becomes a cation).When an atom gains electrons, it becomes negatively charge as there are more electrons than protons (becomes an anion).

3.1.5 Apply the periodic table to predict the ions formed by atoms of metals and non-metals

Group 1 metals (Li, Na, K, Rb, Cs) all tend to lose one electron and therefore form singly charged positive ions: Li+, Na+, K+, Rb+, Cs+. Group 2 metals (Be, Mg, Ca, Sr, Ba) tend to lose two electrons and therefore form doubly charged positive ions: Be2+,Mg2+, Ca2+, Sr2+, Ba2+. Group 3 elements except for boron tend to lose three electrons and therefore form cations: Al3+, Ga3+, In3+. Group 6 elements (non-metals, O, S, Se, Te) tend to gain two electrons and thus form doubly charged negative ions: O2-, S2-, Se2-, Te2-.

Group 7 elements (non-metals, F, Cl, Br and I) all tend to gain one electron and therefore they form singly charged negative ions: F-, Cl-, Br-, I-. Group 8 elements (non-metals; inert gases) will not form ions.  The transition metals all lose electrons to form positive ions (for example Cr3+, Fe2+,Cu2+, Ag+, Zn2+), but it is not possible from a simple look at the Periodic Table to predict just how many electrons any particular atom will lose

3.1.6 Apply Lewis electron dot structures to:
- The formation of ions
- The electron sharing in some simple molecules

Electron sharing (covalent)

3.1.7 Describe the formation of ionic compounds in terms of the attraction of ions of opposite charge Ionic bonds involve atoms losing and gaining electrons, thus forming ions (charged atoms).The attraction of opposite charges (electrostatic force) is what brings ions together to form an ionic compound. 3.2.2 Construct ionic equations showing metal and non-metal atoms forming ions

3.1.8 Describe molecules as particles which can move independently of each other Molecules are particles that may move independently of each other. The forces that hold the molecules together are known as intermolecular forces. If these forces are weak the molecules may move independently of each other. However if these forces are extremely strong the molecules maybe tightly bound and their movement maybe restricted to just vibrations.

3.1.9 Distinguish between molecules containing one atom (the noble gases) and molecules with more than one atom Monatomic molecule:  The noble gases are atoms which exist as independent atoms and don’t need to join with another atom to become diatomic as they have a full outer shell. Examples are neon and helium Diatomic molecule: Is a pair of atoms permanently stuck together to form molecules e.g. oxygen gas (O2). They from a diatomic molecule as they have covalent bonds to attain full outer shells. Metals cannot form diatomic molecules as covalent bonds are needed for diatomic molecules. 3.1.10 Describe the formation of covalent molecules in terms of sharing of electrons Covalent bonds are attractive forces between atoms that occur because the atoms are sharing one or more pairs of electrons. The shared pair of electrons orbits the nuclei of both atoms, thus holding the atoms together and form a covalent compound.

3.1.11 Construct formulae for compounds formed from:
- Ions
- Atoms sharing electrons

Atoms sharing electrons (covalent)

1.1.7 Apply systematic naming of inorganic compounds as they are introduced in the laboratory Ionic compounds:
* Write the name of the metal first
* Write the beginning of the non-metal
* Add ‘’-ide’’ as the suffix to the non-metal
Covalent compounds:
* Use the normal element name for the first element and add the ‘’-ide’’ suffix for the second element * The first element named is the one that occurs further to the left of the periodic table * If both the elements occur in the same group, the one lower down the group is named first (exception oxygen is always named last, except when with fluorine) * The prefixes mono (1), di (2), tri (3) etc. are added to the front of each word to indicate the number of atoms present in each type 1.1.8 Identify IUPAC names for carbon compounds as they are encountered

Series | Suffix | General formula | Type of bond |
Alkane | -ane| CnH2n+2| Single bond|
Alkene | -ene| CnH2n| Double bond |
Alkyne | -yne | CnH2n-2| Triple bond|

Prefix| No. of carbon|
Meth | 1|
Eth | 2|
Prop | 3|
But | 4|
Pent | 5|
Hex | 6|
Hept | 7|
Oct| 8|
Non | 9|
Dec | 10|

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