Appendix - Background info
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| An atom consists of | of a nucleus->containing protons and neutrons->they are surrounded by a cloud of electrons. | (blank)
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| Proton | has a (+) charge, the No of protons (referred to as the atomic number) determines the nature of the atom. | (blank)
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| Neutrons | Neutrons have a similar mass to protons, but they do not have a charge. | (blank)
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| Atomic mass | of an atom us equal to the combined mass of the protons and neutrons.->Atoms that occur naturally on the Earth contain from 1-92 protons. | ie. Hydrogen atom has only one proton in its nucleus, oxygen has 8. Electrons have very little atomic mass.
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| Hydrogen atom | has only one proton in its nucleus | (blank)
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| Atomic charges | the positive charges in the nucleus of an atom are balanced by negatively charged electrons. |
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| Electrons | have very little mass (only about 1/1840 of the mass of a proton.Sometimes electrons may be lost by an atom->atomic charge is no longer balanced. | (blank)
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| Ion | an atom in which the number of electrons does not equal the number of protons. ->Ions have an overall charge:-if electrons are lost the ion will be positive charged, if electrons are gained, the ion will have negative charge. | i.e. if atom of potassium lost an electron it becomes a (+) charged potassium ion (written K+); a chlorine atom (Cl) that gains an elect.->chloride ion (Cl-)
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| Chemical Symbol K | Potassium | (blank)
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| What does the equation "K -> K+ + e-" stand for? | that is an atom of potassium becomes a potassium ion by losing an electron. | (blank)
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| What does the equation "Cl + e- -> Cl-" stand for? | that is, a chlorine atom becomes a chloride ion by gaining an electron. | (blank)
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| What are the Calcium and Magnesium ions? | they both form ions by losing 2 electrons, so Ca-ion and Mg-ion both have 2 (+) changes . | (blank)
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| Cation | used for an ion with a positive charge | (blank)
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| Anion | used for an ion with a negative charge. | (blank)
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| Atoms | there are 92 naturally occuring types of atomes->they are refered to as elements. | (blank)
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| Elements | they each have a characeristic No of protons in thier nucleus->which gives the element its atomic number | (blank)
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| Atomic Number | is the same as ther characeristc number of protons. | (blank)
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| Molecule | relatively few substances occur naturally in the form of a pure element->most atoms are combined to form a stable structure referred to as a molecule. | Molecules often consist of more than 2 atoms. One reason why larger molecules form is that an atom may be able to share electrons with more than 1 atom.
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| Atoms join together to form molecules by: | 1. gaining one of more electrons, 2. losing one or more electrons, 3. sharing electrons with another atom. | (blank)
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| Positive Ion | when an atom loses an electron it becomes a positive ion | (blank)
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| Negative Ion | when an atom gains an electron it becomes an negative ion. | (blank)
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| Electher in their rovalent bond | => ionic bond. ->Opposite charges, that is, negative and positive, attract each other so that a positively charged ion and a negative charged ion will be held together by the attratction of opposite charges, forming an electrovalent bond. | (blank)
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| Covalent bond | result then 2 atoms share one or more pairs of electrons, thus forming a covalent bond. | ->when 2 atoms share 1 or more pairs of electrons.->a covalent bond is formed when 1 atom shares 1 or more pairs of electrons with another atom.->covalent bonds are stronger than electrovalent bonds!
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| Chemical bond | is a force which holds 2 atoms together. -> reults from the attraction of opposite charges->referred to as an electrovalent bond, or from sharing of 1 or more pairs of electrons->as in a covalent bond. | (blank)
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| Sodium chlorine | ->common table salt (NaCl) consists of reluar arrangements of sodium ions (Na+) and chloride ions (Cl-) held together by electrovalent bonds | the (+) and (-) charges of the ions attract each other & the sodium and chloride ion cluster together to form a crystal of salt, which is typically cube-shaped.
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| Explain why salt dissovels in water | water molecules break up the forces holding the ions together in their crystal structure and the salt dissoves to form a solution containing an mixture of free sodium ions (Na+) and free chloride ions (Cl-). | (blank)
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| double bond | when 2 atoms are joined by sharing 2 pairs of electrons | i.e. molecules formed by 2 atoms joined together for example osygen gas (O2), which consists of 2 atoms of oxygen, joined by the sharing of 2 pairs of electrons.
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| Organic substances | they ALL contain carbon atoms (C) and hydrogen (H) atoms.-> Each carbon atom can form 4 covalent bonds. | ie. when caron forms 4 single covalent bonds with 4 atoms of hydrogen (H) to produce molecule of methan (CH4).
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| Which are the 4 most common atoms which are found the most often in the 11 atoms are commonly found in living organisms? | 1. carbon (C), 2. oxygen (O), 3. hydrogen (H), 4. nitrogen (N), | (blank)
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| How many covalent bond do oxygen and nitrogen form? | Oxygen form 2 covalent bonds and nitrogen 3. | (blank)
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| What is the molecular formula of glucose? | C6H12O6 | (blank)
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| What does water consists of? | of an atom of oxygen covalently bonded to 2 hydrogen atoms. | ->the oxygen atom is surrounded by a stable arrangement of 8 (-) charged electrons
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| Polar | a water molecule is described as being polar bcs the charges ens. | (blank)
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| hydrogen bonds | the weak forces of attraction between partially positive (+) charges and partially negative (-) charges are referred to as hydrogen bonds. | many of the important properties of water result form the molecule having electon-rich/poor regions->giving part. (+)/(-)poles. ->weak forces of attraction between part. (+)/(-)charges.
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| What are the different properties of water? | 1. it is cohesive (adhesive), 2. water stores heat, (it has a high spedific heat), 3. large input of heat is needed to convert w. into vapour, 4. it acts as a solvent, 5. Water ionises | (blank)
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| Cohesion | Water molecules tend to cling to each other and to other polar molecules. Attraction between water molecules is referred to as cohesion. | (blank)
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| Adhesion | Water molecules tend to cling to each other and to other polar molecules. Attraction between water molecules and OTHER polar molecules is referred to as adhesion. | (blank)
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| latent heat of vaporisation | large input of heat is needed to convert w. into vapour | evaporation of water has a significant cooling effect. ->this is why evaporation of sweat is an important mechanism in the regulation of body temperature.
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| hydration shell | is the process that each ion becomes surrounded by a cloud of water moleculesell | Water molecules form a hydration shell around any molecule which has an electrical charge (ie. ion, partial/full elec. charge)->hydration shells form around ALL POLAR molecules when they dissolve in water. ->they are soluble in water.
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| Why does glucose dissolve in water? | bcs. water molecules form hydrogen bonds with the polar hydroxyl group, resulting in the glucose molecules being surrounded by a hydration shell. | (PS: Nonpolar molecules, such as fats, adn oils are NOT soluble in water)
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| Solubility | is defined as the maximum concentration that can be obtained of a substance when it is dissolved in a solvent. | hydration shells are soluble in water because the form around ALL POLAR molecules.
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| Ionisation | is the process when covalent bonds (between oxygen and hydrogen in water molecules) sometimes break, resulting in the formation of a proton (H1) and a hydroxide ion (OH-). | this process is represented by following chemical equation: H2O -> H(+) + OH(-)
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| solvent | is a liquid, such as water, in which other substances can disolve. | For example glucose (->solute) dissolves in water (->solvent) to form a solution.
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| solute | the substance which dissolves in the solvent is referred to as the solute. | For example glucose (->solute) dissolves in water (->solvent) to form a solution.
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| What are the "rules" of how to write chemical equations? | 1. we write the reactants on the left of the equation, 2. and the products on the right. 3. No of atoms need to be the same on both sides, | (blank)
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| Oxydation | is the LOSS of an electron/hydrogen by an atom, ion or molecule and is often accompanied by the loss of a hydrogen (H+) ion | (blank)
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| Reduction | is the GAIN of an electron/hydrogen -> the electron lost by one molecule is transferred to another. This process is called reduction. i.e. respiration involves individuall reactions | in which the substrate is oxidised by the transfer of hydrogen from the substrate to a hydrogen carrier. In this way the substrais oxidised and the hydrogen carrier is simultaneously reduced when it accepts the hydrogen.
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| Condensation Reaction | when 2 substances are combined by the removal of water. ->covalent bind is formed->reactions occur when for ex. 2 monosaccharid join to form a disaccharid->i.e. glucose+fructose join together by means of cond. reactions to formi sucrose. | reactions are important bcs. simple molecules can be joined in this way->forming large molecules->i.e. polysaccharide such as starch.
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| The Principle the chemical formula of condensation reaction | "A"-OH + "B"-H -> "A-B" + H2O | notice that OH is removed from A and H from B; H and HO join together to form water H2O. -> Substances A and B are now joined together hy means of covalent b
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| Peptide Bond | a covalent bond between the amino acids is known as a peptide bond. | if process is repeated ->progressively adding further amino acids -> to build up polypetide->each time a peptide bond is formed a molecule of water is released.
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| Glucose | Organic compound, a simple sugar (monosaccharide), chemical formula C6H12O6. | (blank)
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