Chemistry Topic 7 and 8

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T7- What structures do ionic substances always form?
GIANT IONIC STRUCTURES/LATTICES
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T7- Describe an ionic crystal
A giant 3D lattice structure held together by the attraction between the oppositely charged ions.
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T7- What are the features of a giant ionic structure and why?
A high melting point because the strong electrostatic attraction between opposite ions reuires high energy to overcome. Ions are closely packed due to the attraction.
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T7- What is the correlation between the charge of the ion and the boiling point? why?
The higher the charge of the ions, the stronger the forces of attraction holding the lattice together. Higher energy is needed to over come this attraction, so a higher boiling point.
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T7- When does a covalent bond form?
When two atoms share one pair of electrons so that they both have a full outer shell.
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T7- Which type of elements form covalent bonds?
Non-metals
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T7- What is one covalent bond?
ONE pair of shared electrons (an electron from each atom.)
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T7- What is covalent bonding?
The covalent bond is a strong attraction between the bonding pair of electrons shared, and the nuclei of the atoms involved in the bond.
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T7- What are the properties of simple molecular structures and why?
Simple molecular structures are usually gases or liquids at room temperature as they have low boiling points. This is because despite strong covalent bonds within the molecules, there are weak intermolecular forces. Require less energy to overcome
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T7- What are the properties of giant covalent structures?
Highmelting point because all the atoms have strong covalent bonds, and high energy is needed to overcome THE MANY of them. They are usually insoluble in water and not not conduct electricity even when molten.
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T7- What are the properties of diamond and why?
It is extremely hard because each carbon atom is joined to another by 4 covalent bonds and therefore the structure is rigid and regular.
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T7- What are the properties of graphite and why?
Graphite can be used as a lubricant or to conduct electricity as each carbon only has three covalent bonds and the electrons not bonded can conduct electricity. Also the three covalent bonds cause layers which can slide, so it can be a lubricant.
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T8- Define the term isotope.
Isotopes are different atomic forms of the same element, which have the same number of protons, but a different number of neutrons.
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T8- Define relative atomic mass
It is the average mass of all the isotopes of one element, compared with the mass of carbon-12. It also allows for the abundance of the isotopes.
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T8- What is the formula to work out the relative atomic mass?
(isotope x abundance) + (isotope x abundance) / 100 (or the sum of the ratios)
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T8- When is the relative formula mass used?
When you want to work out the mass of a compound.
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T8- How do you calculate the relative formula mass?
You add up the (relative) atomic masses of all the elements in the compound.
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Card 2

Front

T7- Describe an ionic crystal

Back

A giant 3D lattice structure held together by the attraction between the oppositely charged ions.

Card 3

Front

T7- What are the features of a giant ionic structure and why?

Back

Preview of the front of card 3

Card 4

Front

T7- What is the correlation between the charge of the ion and the boiling point? why?

Back

Preview of the front of card 4

Card 5

Front

T7- When does a covalent bond form?

Back

Preview of the front of card 5
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