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GCSE chemistry and combined chemistry
Question | Answer |
---|---|
Why do atoms transfer electrons in ionic bonding? | So that they can have full outer shells |
Explain in terms of electrons what occurs when lithium bonds with fluorine | One electron transferred from lithium to fluorine |
Explain in terms of electrons what occurs when magnesium bonds with oxygen | Two electrons transferred from magnesium to oxygen |
Explain in terms of electrons what occurs when beryllium bonds with oxygen (3 marks) | Two electrons transferred from beryllium to oxygen |
Explain in terms of electrons what occurs when magnesium bonds with chlorine | One electron transferred from magnesium to two different chlorine atoms |
Explain in terms of electrons what occurs when sodium bonds with oxygen | Two electrons transferred to an oxygen atom from two different sodium atoms |
Why do sodium ions and chlorine ions form an ionic bond? | There is an electrostatic force of attraction between oppositely charged ions |
Why don't sulphur ions and oxygen ions form ionic bonds with each other? | Both have negative charges so would repel |
What is the name for a substance made of billions of oppositely charged ions joined together? | Giant ionic lattice |
Define giant ionic lattice | A huge 3D network of ions |
State the melting points of ionic substances | High |
Explain why ionic substances have high melting points. | Strong bonds between oppositely charged ions are hard to break |
Will NaCl(s) conduct electricity? | No |
Will NaCl (aq) conduct electricity? | Yes (aq stands for aqueous which means it is dissolved in water) |
Will NaCl (l) conduct electricity? | Yes |
What does molten mean? | Melted |
Explain why ionic compounds do not conduct electricity when solid | Because the ions are not free to move |
Explain why ionic compounds conduct electricity in solution | Because the ions are free to move |
Explain why ionic compounds conduct electricity when molten | Because the ions are free to move |
Explain why chlorine and fluorine form covalent bonds | They are both non-metals |
Complete the sentence: In covalent bonds, electrons are _______________________ | Shared |
In ionic bonds, electrons are ___________________ | Transferred |
What is the name given to the structure of diamond, graphite and silicon dioxide? | Giant covalent |
How many bonds does each carbon have in diamond? | 4 |
Explain why diamond has a high melting point | Giant structure, Strong covalent bonds between the atoms, requires a lot of energy to break |
Explain why most giant covalent substances do not conduct electricity (3 marks) | There are no electrons/ions/charged particles that are free to move |
Explain why graphite conducts electricity | Has delocalised electrons between the layers that can move through the graphite |
Explain why graphite can act as a lubricant | Weak forces between layers which are free to slide over each other |
What is graphene? | One layer of graphite |
What is a fullerene? | Substance made of carbon atoms arranged in a cage |
What type of substance are methane and water? | Simple molecular (or simple molecules) |
What is a molecule? | A group of atoms chemically bonded together |
Describe the structure of simple covalent molecules | Strong covalent bonds between atoms, weak forces holding the molecules together |
What are intermolecular forces? | Weak forces between molecules which hold them together |
Explain why methane has a low melting point | It is a simple molecular substance with weak forces between the molecules (which are easy to break) |
What is a polymer? | Millions of small molecules joined together in a chain to form a large molecule |
Describe the main features of metals in terms of their structure | Positive metal ions arranged in layers with delocalised electrons |
Explain why metals can conduct electricity | Delocalised electrons are free to carry charge |
Explain why pure metals are soft | Layers of metal ions are free to slide over each other |
Explain in terms of electrons what occurs when lithium bonds with chlorine | One electron transferred from lithium to chlorine |
What charge will an ion of lithium take? | 1+ (one electron in the outer shell, needs to lose it) |
What charge will an ion of beryllium take? | 2+ (two electrons in the outer shell, needs to lose them both) |
What charge will an ion of barium take? | 2+ (group 2 so two electrons in the outer shell, needs to lose them both) |
What charge will an ion of fluorine take? | 1- (7 electrons in the outer shell, needs to gain one) |
If something has gained electrons, what charge will it have? | Negative |
If something has lost electrons, what charge will it have? | Positive (because they have lost a negative!) |
What charge will an ion of oxygen take? | 2- (6 electrons in outer shell so needs to gain two) |
What is an ion? | an atom which has lost or gained an electron |
How many electrons, protons and neutrons in a sodium ion Na+ ? | 11 protons, 12 neutrons, 10 electrons |
What are the limitations of dot and cross diagrams. | It does not show the shape of the molecule or the size of the atoms. |
If a compound name ends in -ate what does this show? | It is a molecule made of the other elements in the name and oxygen. |
What are the limitations of a ball and stick model | It does not show the electrons involved in the bonds. It does not show the 3d shape |
What elements are in sodium sulfate? | Sodium, sulfur and oxygen |
If a compound name ends in -ide what does this show? | It is a molecule made of 2 elements only. |
How many electrons, protons and neutrons in an oxygen ion O2- ? | 8 protons, 8 neutrons, 10 electrons |
How many electrons, protons and neutrons in a chloride ion Cl- ? | 17 protons, 18 neutrons, 18 electrons |
How many electrons, protons and neutrons in a magnesium ion Mg2+ ? | 12 protons, 12 neutrons, 10 electrons |
What elements are in potassium hydroxide? | potassium, oxygen and hydrogen |
What elements are in sulfuric acid? | hydrogen, sulfur and oxygen |
What elements are in iron carbonate | iron, carbon and oxygen |