9278485
Description
Flashcards by Natalia Cliff, updated more than 1 year ago
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Created by Natalia Cliff
almost 7 years ago
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| Question | Answer |
| Draw a sodium Ion |
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Sodium Ions (image/gif)
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| Draw a water molecule |
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Water Molecule (image/gif)
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| Draw a metal |
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Metalic Bonding (image/gif)
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| What are compounds? | Substances in which atoms of two or more elements are chemically combined |
| What does chemical bonding involve? | Either transferring or sharing electrons in the highest occupied shells of atoms in order to achieve the electronic structure of a noble gas |
| How are ions formed | -By the transferring of electrons -Atoms that lose electrons become positively charged -Atoms that gain electrons become negatively charged -Ions have the electronic structure of a noble gas |
| What do Alkali Metals react with? | -Alkali Metals (group one) react with Halogens (group seven) -This forms ionic compounds -Alkali Metals have a single positive charge as they lose one electron -Halogens have a single negative charge as they gai one electron |
| What are ionic compounds | -A giant structure of ions -Ionic compounds are held together by strong electrostatic forces of attraction between oppositely charged ions -These forces act in all directions in the lattice -This is called ionic bonding -Ionic bonding occurs between metals and nonmetals |
| Sodium Chloride structure |
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Sodium Chloride (image/gif)
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| What is Covalent bonding? | -Forms when atoms share electrons -Bonds between the atoms are very strong -Occurs between nonmetals -Can form simple molecules like Cl2, H2, O2, HCl, H2O, NH3, CH4 -Can also called giant covalent structures (macromolecules) like diamond and silicon dioxide |
| What are metals made of? | -Giant structure of atoms arranged in a regular pattern -The electrons in the outermost shell of metal atoms are delocalised and so free to move about -Structure of positive ions with delocalised electrons between the ions holding them together by strong electrostatic forces of attraction |
| Properties of simple molecules | -Relatively low melting and boiling points -Because of weak intermolecular forces despite strong covalent bonds -It's these intermolecular bonds that need to be overcome for the substance to be molten or boiled -Don't conduct electricity as they have no overall electrical charge |
| Properties of Ionic Compounds | -Ionic compounds have regular structures (giant ionic lattices) -Strong electrostatic forces in all directions between oppositely charged ions -High melting and boiling points because of the large amount of energy needed to break the many strong bonds -When molten or dissolved in water can conduct electricity because the ions are free to move and carry the current |
| Properties of Covalent Structures | -Also formed by covalent bonds -For example Diamond, Graphite and silicon dioxide (Silica) -All of the atoms are linked to each other by very strong covalent bonds -Very high melting points |
| Properties and structure of Diamond | -Each carbon atom bonds with four other carbon atoms -This makes diamond very strong |
| Properties and structure of Graphite | -Each carbon atom bonds with three other carbon atoms -The final carbon in the outer shell is delocalised -This allows graphite to conduct electricity and heat |
| What are fullerenes? | -Carbon can also form fullerenes with different numbers of carbon atoms -Fullerenes structure is based on hexagonal rings of carbon atoms |
| What are fullerenes used for? | -Used for drug delivery in the body (stops potentially toxic drugs affecting other parts of the body as it's covered by carbon fullerenes) -In lubricants (same sliding properties as graphite) -As catalysts (spreading a catalyst over it gives it a large surface area) -As nanotubes for reinforcing materials as it is strong -They also have the delocalised |
| Properties of metals | -Conduct heat and electricity because the delocalised electrons are free to move throughout the structure -Layers of ions in metals can slide over each other so the metal can be bent and shaped |
| Structure and properties of Alloys | -Usually made from two or more different metals -Different sized ions of the metals distort the layers in the structure -Makes it more hard for them to move over each other -Hence alloys are harder than pure metals -Shape memory alloys can return to their original shape after being deformed -E.g. nitinol can be used in dental braces |
| What do the properties of polymers depend on? | -Properties of polymers depend on the conditions they were made under -E.g. Low Density and High Density poly(ethene) are made using different catalysts and reaction conditions |
| Types of polymers | -Thermosoftening polymers consist of individual tangled polymers chains, melt when heated because of weak intermolecular forces -Thermosetting polymers consist of polymer chains with cross-links between them, so they don't melt when heated -Thermosoftening and thermosetting polymers can be high density or low density |
| What is Nanoscience? | Refers to structures that are 1-100 nm in size, or a few hundred atoms -Have different properties to the same material in bulk and have a high surface area to volume ratio |
| Why is Nanoscience useful? | May be used to develop: -New Computers -New Catalysts -New Coatings -Highly Selective Sensors -Stronger and Lighter Construction Materials -New Cosmetics -Deodorants |
| Atomic Structure | Check out the C1 flashcards if you really don't know that atoms are made from neutrons protons and electrons |
| What is an atom's Relative Atomic Mass (Ar)? | -A measurement of the mass of one atom of an element -Found by comparison with the 12C Isotope -An average value for the isotopes of the element |
| What is the Relative Formula Mass (Mr)? | The relative formula mass of a compound is the sum of the relative atomic masses of the atoms shown in the formula |
| What are Moles? | The relative formula mass of a substance, in grams, is one mole of that substance |
| If you have problems understanding moles, this explanation is by Randall Munroe, I found it helpful | A mole is a unit. It’s not a typical unit, though. It’s really just a number — like “dozen” or “billion.” If you have a mole of something, it means you have 602,214,129,000,000,000,000,000 of them (usually written 6.022×1023). It’s such a big number because it’s used for counting numbers of molecules, which there are a lot of. |
| Instrumental Methods | -Elements and compounds can be detected and identified using instrumental methods -Instrumental methods are accurate, sensitive and rapid -Particularly useful when the sample is very small |
| Chemical Analysis | -Can be used to identify additives in foods -Artificial colours can be detected by paper chromatography |
| Paper Chromatography | -Put ink dots on a straight pencil line at the bottom of a piece of paper -Put the bottom of the piece of paper into water |
| What is Gas Chromatography | -An instrumental method -Allows the separation of a mixture of compounds -The time taken for a substance to travel through the column can be used to help identify substances |
| How does Gas Chromatography work? | -Different substances are carried by a gas -Travel through a column packed with a solid material at different speeds, so they separate -The number of peaks on the output of a gas chromatograph shows the number of compounds present -The position of the peak indicates retention time |
| Mass Spectronomy | -The output of a gas chromatography column can be linked to a mass spectrometer, which can identify the substances leaving the column -It can also give the relative atomic mass of each substance that is separated in the column -Can identify substances very quickly, accurately and from small quantities -Molecular Mass is given from the molecular ion peak |
| Calculating the percentage of an element in a compound | Relative mass of the element in the compound over the relative formula mass of the compound |
| Empirical Formula | -It's a ratio of the number of elements in a compound -G=mxr where G is grams, m is moles and r is relative atomic mass |
| Why may you not get 100% yield? | Even though no atoms are gained or lost: -The reaction may be reversible and so not complete -Some product may be lost when it is separated from the reaction mixture -Some of the reactants may react in different ways to expected |
| What is a percentage yield? | -The amount of product obtained is known as the yield -When compared to the maximum theoretical yield, it is called percentage yield |
| What is a reversible reaction? | A reaction where the products can react to produce the original reactants E.g. ammonium chloride to ammonia and hydrogen chloride is a reversible reaction |
| How can you find the rate of reaction? | -Either amount of reactant used over the time taken -Or the amount of product formed over the time taken |
| When do chemical reactions occur? | When, and only when, particles collide with each other with sufficient energy |
| What is activation energy? | The minimum amount of energy particles need to react |
| What factors increase the rate of reaction? | -Temperature, increases energy so more and more successful collisions -Pressure, increases frequency of collisions -Concentration of reactants, increases frequency of collisions -Surface area, increases frequency of collisions -Catalysts speed up the rate of reaction without getting used up but different reactions need different catalysts, used in the industry to reduce costs |
| What happens when chemical reactions occur? | Energy is transferred to the surroundings |
| What is an exothermic reaction? | -A reaction that transfers energy to it's surroundings -E.g. combustion, many oxidisation reactions and neutralisation -Everyday uses include self-heating cans and hand warmers |
| What is an endothermic reaction? | -A reaction that takes in energy from it's surroundings -E.g. thermal decomposition -Everyday uses include some sports injury packs |
| Energy change in reversible reactions | If a reversible reaction is exothermic one way, it will be endothermic the other way. The same amount of energy is transferred in each case |
| Copper Sulphate reaction |
need to know, including colour
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Copper Sulphate (image/jpeg)
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| What are the state symbols in equations? | -(s) is solid -(l) is liquid -(aq) is aqueous solution |
| What are the different reactions for salts? | -Acid + Base -> Metal Salt + Water -Acid + Metal -> Metal Salt + Hydrogen -Soluble Salt + SOluble Salt -> Insoluble Salt |
| Acids and Alkalis Method | -Put 10 ml of acid in beaker -Add a few drops of universal indicator -Add Alkali slowly, drop by drop, stirring whilst doing so -Stop when solution turns green -Record the volume of ALkali added -Repeat procedure with clean equipment but no universal indicator -Put solution in an evaporating basin and evaporate |
| Acids and Metals Method | -Place 25 ml of acid in a boiling tube -Add metal and note occurring reaction -Filter the solution into an evaporating basin -Leave in a warm place to evaporate |
| Soluble Salts Method | -Place 10 ml of a soluble salt in a beaker -Add 10 ml of another soluble salt -A precipitate will be formed -Filter the mixture with filter paper and a funnel -Rinse the precipitate in the filter with distilled water -Remove the participate from the filter paper with a spatula and place on glass to evaporate |
| How can you turn a salt solution into a solid salt | Crystalise it |
| How can you remove unwanted ions from solutions? | -Insoluble salts can be made by mixing appropriate solutions of ions so that a precipitate is formed -Precipitation can be used to remove unwanted ions from solutions -E.g. treating water for drinking of treating effluent |
| What are bases and alkalis? | -Metal oxides and hydroxides are bases -Soluble hydroxides are alkalis |
| What does the particular salt formed in an acid and base/alkali reaction depend on? | -The acid used (hydrochloric acid produces chloride, nitric acid produces nitrates and sulfuric acid produces sulfates) -The metal in the base/alkali |
| What is ammonia used for? | -Ammonia dissolves in water to produce an alkaline solution -It is used to produce ammonium salts -Ammonium salts are important fertilisers |
| The ions in acids and alkalis | -Hydrogen ions H+(aq), make solutions acidic -Hydroxide ions OH-(aq) make solutions alkaline -In neutralisation reactions these ions react to form water |
| PH scale | -Measure of acidity or alkalinity of a solution -7 is neutral -Beneath 7 is acidic -Over 7 is alkaline |
| What happens when ionic substances are melted or dissolved? | The ions are free to move around in the liquid or solution |
| What does passing an electrical current through this do? | -Passing an electric current through ionic substances that are molten (e.g. lead bromide) breaks them down into elements --This is called electrolysis -The substance being broken down is called the elctrolyte |
| What happens in electrolysis | -Positively charged ions move to the negative electrode (cathode) -Negatively charged ions move to the positive electrode (anode) -At the negative electrode positively charged ions gain electrons (reduction) -At the positive electrode negatively charged ions lose electrons (oxidation) -If there is a mixture of ions, the product formed depends on the reactivity of elements involved |
| What is electrolysis used for? | -Used to Electroplate objects -This may be for a variety of reasons and includes copper and silver plating |
| Half equations | -Reactions at electrodes can be shown as half equations e.g. 2Cl- --> Cl2 + 2e- |
| Electrolysis of Aluminium | -Aluminium is manufactured by the electrolysis of a molten mixture of aluminium oxide and cryolite -Cryolite is used as aluminium has a very high melting point, so it's dissolved in molten cryolite -Aluminium forms at the negative electrode -Oxygen forms at the positive electrode -Positive electrode is made of graphite (carbon) which reacts with oxygen to produce carbon dioxide -Hence the positive electrode needs to be replaced ever so often |
| Electrolysis of Aluminium Diagram |
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Aluminium (image/gif)
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| Electrolysis of brine | -Brine is sodium chloride solution -This process produces hydrogen and chlorine -Sodium hydroxide solution is left behind -These are important reagents for the chemical industry -E.g. sodium hydroxide is used in the production of soap and chlorine for bleach and plastics |
| Predicting the Products of Electrolysis | At the Negative Electrode: -Metal will be produced if it is more reactive than hydrogen -Hydrogen will be produced if the metal is less reactive than hydrogen At the Positive Electrode: -Halide ion will form -If halide ion not present then oxygen will form |
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