Chemistry exam 6/3/14 – Flashcards

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Properties of Metallic Bonding
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  • Positive ions surrounded by a 'sea' of delocalised electrons
  • Strong attraction between ions and delocalised electrons
  • High melting points
  • Almost all are solid at room temperature
  • Conduct electricity
  • Conduct heat
  • Malleable
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Examples of Metallic Bonds:
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Any metallic element has metallic bonds:

  • Sodium
  • Copper
  • Zinc
  • Sodium
  • Lithium
  •  Francium
  • Iron
  • Cobalt
  • Calcium
  •  Magnesium
  • Silver
  • Gold
  • Barium
  •  Platinum

and

  • Chromium

are a few.

If you named at least 3 then well done.

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Properties of Giant Ionic Structures:
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  • Regular 3D arrangement of positive and negative ions
  • Strong electrostatic attraction between positive and negative ions
  • High melting points
  • Always solid at room temperature
  • Conduct electricity when molten and in solution
  • Regular crystal arrangment
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Examples of Giant Ionic Structures:
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  • Sodium chloride
  • Magnesium oxide
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Properties of a simple covalent structure:
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  • Isolated molecules with weak forces between molecules
  • Strong bonds between atoms, electrons are shared
  • Low melting points
  • Gases and liquids at room temperature
  • Don't conduct electricity
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Examples of simple covalent structures:
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  • Hydrogen
  • Ammonia
  • Methane
  • Water

 

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Properties of Giant covalent structures:
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  • Repeating 3D structure with strong bonds between atoms
  • Strong bonds between atoms, electrons are shared
  • High melting points
  • Always solid at room temperature
  • Most don't conduct electricity (except graphite)
  • Regular crystal arrangement
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Examples of Giant covalent structures:
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  • Graphite
  • Diamond
  • Silica
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Elements react to form compounds by what 3 methods?
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Sharing electrons, giving electrons and taking electrons.
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A metal atom loses electrons and forms _______ ions.
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A metal atom loses electrons and forms positive ions.
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When non-metallic elements join together they form ________ bonds.
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When non-metallic elements join together they form covalent bonds.
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Ionic compounds are held together by ______ ___________ forces between oppositely charged ions.
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Ionic compounds are held together by strong electrostatic forces between oppositely charged ions.
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Why are ionic compounds neutral?
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In an ionic bond, one ion must have a positive charge and one must have a negative charge. When they bond, they resolve their charge imbalances. The sum of the charges of the cation and anion add up to 0.
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When is a covalent bond formed?
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When electrons in atoms are shared.
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Definition of delocalised?
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The electrons can move about freely between atoms.
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What happens when a metal reacts with a non-metal?
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The metal atoms lose electrons and become positive ions, and the non-metal atoms gain electrons and become negative ions.
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ANIONS are negative.
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CATions are positive.

Try remembering is as positive...pawsitive...pursitive...cat! And cats are great, so it's positive.

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What is a compound?
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A bonded substance made from two or more elements that have reacted chemically with each other.
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What is an element?
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A substance that contains only one type of atom depending on the amount of protons in it's nucleus.
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What is an atom?
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The smallest particle of a chemical element that can exist. An atom will do anything to get a full outer shell.
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How many electrons are in the 1st, 2nd and 3rd shells in an atom?
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1st shell = 2 electrons

2nd = 8 electrons

3rd = 8 electrons

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Difference between an atom and an ion?
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An atom has an equal amount of protons and electrons, and no charge.

Ions do not have an equal amount of protons and electrons, but has a full outer shell.

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Does an ionic compound have a charge?
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NO, it has zero charge.
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What is ionic bonding?
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When a cation (positive charge, full outer shell) bonds/attracts with an anion (negative charge, full outer shell)
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What is a polymer?
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  • Polymers are very big molecules with long chains of carbon atoms.
  • Plastics are examples of polymers.
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What do the properties of a polymer depend on?
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The structure and bonding found in their molecules.
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What is the difference between thermosoftening polymers and thermosetting polymers?
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Thermosoftening  polymers

Thermosetting polymers

Hard when cold

Flexible when cold

Flexible when warm/hot

Hard when warm/hot

Can be moulded and re-moulded many times because the bonds between molecules are very weak

Once heated, melted, and moulded, it cannot be remoulded because the bonds between molecules are too strong

Can be shaped many times.

Can only be shaped once.

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How big is a nanometre?
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Once billionth of a metre.
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What risks/worries/issues arise from the use of nanoparticles?
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  • Evidence that they could be damaging to lifeforms
  • Studies have shown that nanoparticles can be toxic to animal cells
  • It has been considered that exposure can cause breathing problems, and since they are small enough to be inhaled through the nose, and go straight through the nasal passage to the brain, they can cause a lot of damage there
  • They can easily enter your blood stream and cause harm
  • Not enough is known about them, so they are not allowed to be used
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What is the mass number?
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Total number of protons and neutrons an element contains.
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What are isotopes?
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Atoms of the same element but with different numbers of neutrons.
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Relative atomic mass and relative formula mass symbols?
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Relative atomic mass = Ar

Relative formula mass = Mr

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How do you calculate a percentage yield?
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   (Amount of product collected)   

(max. amount of product possible)

 

X 100 = Percentage yield

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What is the collision theory?
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Chemicals form compounds through interacting with each other.

 

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What is he minimum amount of energy required to react called?
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Activation energy
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Name 3 things that will increase the rate of a reaction.
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  • Increasing the concentration of one reactant
  • Increasing the temperature
  • Use a catalyst
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What happens when you increase the surface area of a solid (for a reaction)?
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Increases the reaction rate.
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When is a reaction exothermic?
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When heat/energy is released.
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When is a reaction endothermic?
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It takes in energy.
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Name the ion produced when acids are added to water.
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Hydrogen ion, H+
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What will neutralise acids?
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Alkalis
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What do alkalis produce when dissolved in water?
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Hydroxide ions, OH-
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What are the pH values of acids?
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0-6
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What are the pH values of alkalis?
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8-14
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When an acid reacts with a base what are the products?
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Salt and water
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How are salts crystallised?
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When the salt is filtered out of the aqueous solution
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What does electrolysis do?
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Break down ionic compounds into elements using electricity.
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Why must the ionic compounds be molten or in solution for electrolysis to work?
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For electrolysis to work, the ions must be free to move. When the ionic compound is in solution, the ions break free from the ionic lattice.
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[Electrolysis]
What does OILRIG stand for?
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Oxidation Is Loss Reduction Is Gain
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