|ionic bonding happens between a ...
|metal and a non-metal.
|in ionic bonding the metal becomes ______ charged ion?
|in ionic bonding the metal becomes a positively charged ion.
|in ionic bonding the non-metal becomes a ______ charged ion.
|in ionic bonding the non-metal becomes a negatively charged ion.
|how do oppositely charged ions arrange them selves in a giant ionic lattice?
|in a regular way.
|2 properties of ionic compounds?
|high melting point high boiling point because a lot of energy is needed to break the strong bonds.
|can ionic compounds conduct electricity when soild?
|no ionic compounds only CONDUCT electricity when dissolved in water or are melted.
|why do ionic compounds conduct electricity when they're liquids?
|when liquid they lave free or delocalised electrons that move around.
|what type of elements does covalent bonding take place between?
|are ions formed during a covalent bond?ni
|no, as no electrons are gained or donated.
|what two methods are used to display atomic structure?
|-dot and cross diagram: Electron shells are drawn as circles, with the electrons on each shown as dots or crosses -the written numbers.example, lithium is 2.1, neon is 2.8.8, and calcium is 22.214.171.124.
|give three examples of simple molecules with covalent bonds.
|hydrogen, ammonia, methane and water .etc
|simple molecules with covalent bonds have very ____A___ bonds between the atoms but much _____B_____forces holding the molecules together.
|A)strong B) weaker
|when you boil/melt water what breaks for it to change form?
|it is it weak intermoleculer forces that break not the strong covalent bonds.
|what type of boiling and melting points do simple molecular substances have.
|low boiling low melting
|what state are most simple covalent molecules in at room temperature.
|gases at room temperature.
|two features of a giant covalent structure?
|very high melting point- e.g.graphite's is 3600 degrees celcuis. variable conductivity-graphite conducts but diamond does not.
|describe graphite structure.
|- Graphite contains layers of carbon atoms. -each carbon atom has 3 bonds leaving one to move around 'freely'.
|Two uses of graphite?
|1)to write with in pencils. 2) as a lubricant eg. bike chains.
|how strong are the forces between the layers of carbon in graphite?
|they are very weak allowing each layer to slide over each over.
|what element is carbon made up of?
|why does diamonds structure mean it is very hard and strong?
|each carbon atom has a full outer shell and is bonded four times instead of graphite's three bonds.
|does diamond conduct electricity?
|no as unlike graphite it does not have any delocalised electrons.
|what is metallic bonding?
|metallic bonding is when two metal elements bond together.
|what does crystalline refer to?
|solid metals are crystalline- the particles are close together and in a regular arrangement.
|what does this image show?
|this image shows that structure of metallic bonding . metals have loose electrons in the outer shells which form a 'sea' of delocalised negative charge around the close-packed positive ions. There are strong electrostatic forces holding the particles together.
|what do we need to know about delocalised electrons?
|- they are not associated with any particular atom. - they move freely - they are what carries electric or heat energy through the metal.
|what do the free electrons allow metal atoms to do?
|slide over each other which is what makes metal malleable and ductile.
|a metal that is able to be hammered or pressed into shape without breaking or cracking.
|a metal that is able to be deformed without losing toughness; pliable, not brittle. (flexible)
|what would be different between two different isotopes of carbon?
|the only difference between two isotope of the same element is the number of neutrons.
|what is the relative mass of a proton, neutron and electron?
|proton 1 neutron 1 electron 0
|how is the atomic mass of an isotope found as they all have different amounts of neutrons?
|it is found by taking a weighted mean average of all the isotopes weights.
|where is relative atomic mass (Ar) found?
|on the periodic table.
|where is relative formula mass (Mr) found?
|is found by adding up all the Ar's of each atom in the compound.
|what does the empirical formula tell us?
|it tells us the simplest ratio of atoms in a compound.
|what is one mole of a substance?
|One mole of a substance is its gram formula mass (GFM). One mole of a substance contains 6.02 x 1023 formula units. This number is known as the Avogadro constant.
|what two things do you need to find the percentage of an element?
|-relative atomic mass -relative formula mass
|define theoretical yield?
|is the max theoretical mass of product in a reaction.
|define the actual yield?
|is the mass of the product when you actually do the reaction.
|define the percentage yield?
|is the ratio of actual mass of products obtained, compared with the max theoretical mass.
|whats the equation used to find the percentage yield?
|percentage yield= (actual mass of product)/(theoretical mass of product)x 100
|what do we use paper chromatography for?
|Chromatography can be used to separate mixtures of coloured compounds.
|explain the process of doing and setting up a paper chromatography experiment?
|. A spot of the mixture is placed near the bottom of a piece of chromatography paper and the paper is then placed upright in a solvent. As the solvent soaks up the paper, it carries the mixtures with it. Different components of the mixture will move at different rates. This separates the mixture out.
|what would a suitable solvent for paper chromatography be?
|what is an RF value?
|Different chromatograms and the separated components of the mixtures can be identified by calculating the Rf value
|how do you calculate the RF value?
|Rf = distance moved by the compound ÷ distance moved by the solvent
|what is retention time?
|it is the time taken to pass through a coloumn.
|when does a chemical reaction take place?
|chemical reactions happen when reactant particles collide with enough energy.
|define an activation energy?
|the energy needed for a reaction to take place.
|what is a reaction time?
|time for the reaction to finish.
|what is the rate of reaction's equation?
|rate of reaction=amount of product formed/time taken.
|what are three factors that may affect the rate of reaction?
|-temperture -concentration/pressure -surface area -catalyst -PH level
|why might temperature affect the rate of reaction?
|energy is transferred to the particles so they move faster, they are more likely to collide with enough energy to react.
|why might concentration/pressure affect the rate of reaction?
|increasing this means that there are more particles in the same volume, making them more likely to collide.
|why might surface area affect the rate of reaction?
|the smaller the SA the less collisions where as a larger SA means more collisions.
|what is a catalyst?
|is a substance which increases the rate of reaction without being changed or used up.
|one benefit of a catalyst?
|it can be used over and over again for a long time.
|does one catalyst work for every reaction?
|no, you have to find the right catalyst for the reaction to work.
|how does a catalyst work?
|a catalyst gives the particles a surface to stick to so that they bump into each other more often. Overal number of collisions is not changed but the number of successful ones increases.
|what is an exothermic reaction?
|a reactions where its products have less energy than its reactants.( gives out energy during the reaction)
|what is an endothermic reaction?
|it is a reaction that has products with more energy than its reactants. (takes in energy during reaction).
|in an endothermic reaction what happens to the surroundings?
|their temp decreases.
|in an exothermic reaction what happens to the surroundings?
|the temperature increases.
|in a reversible reaction if the forward reaction is exothermic then what is the backward reaction?
|what does this sign mean?
|that the reaction is reversible.
|what process is shown in the flow chart?
|the Haber process.
|the haber process is used to make ammonia, what two elements does it require?
|nitrogen and hydrogen.
|what can ammonia be used for?
|fertilizer cleaning fluids floor washes
|the highest yield is gotten by using low temp and high pressure. why aren't these conditions used industrially?
|it can be dangerous as well as very expensive.
|what does the equation look like for making ammonia?
|what is neutralisation?
|when an acid reacts with a base to make salt and water.
|what does an acid+base =?
|what does an acid+metal oxide=?
|what does an acid+metal hydroxide=?
|what do most bases not do?
|most bases do not dissolve in water.
|bases that dissolve in water are called something else. what is it?
|what happens when an acid and a carbonate react?
|acid+metal carbonate=salt+water+carbon dioxide
|when carbon dioxide is produced in a acid+carbonate reaction, what can be seen? how do you make sure that its carbon dioxide?
|1)it causes bubbling during the reaction. 2) pass it through lime water if it turns cloudy carbon dioxide is present.
|two reactive metals that acid will react with?
|when an acid reacts with a reactive metal what is produced?
|salt and hydrogen. acid+metal=salt+hydrogen
|what does hydrogen do during an acidic reaction? how do you test for hydrogen?
|1) it will cause fizzing. 2) you light a splint and place it in a container of the unknown gas, if it makes a pop sound then it is hydrogen.