What is a compound?
When two elements react with each other.
A molecule made up of different elements.
A substance made of two or more elements that are chemically joined together.
Which electrons in an atom are involved in bonding?
The Inner electrons (closest to nucleus).
The outer electrons (highest energy level of shells).
All electrons.
What happens to the electrons in atoms when ionic bonds are formed?
They are lost in the reaction.
They are shared with the other atom - so all atoms have full shells.
They are transferred (metal lose electron, non-metal gains electron)
What happens to electrons in atoms when covalent bonds are formed?
They are shared (for each covalent bond, a pair of electrons is shared)
They are transferred (metal atom loses electron, non-metal atom gains electron)
Outer electrons are lost in reaction.
Why do the elements in group 1 form ions with a single positive charge?
They gain an electron, which means its charge becomes positive.
They lose one outer electron (which has a negative charge, so charge becomes positive)
They gain protons in it's nucleus so its charge becomes positive.
Why do elements in group 7 form ions with a single negative charge?
They lose their seven electrons which makes the atom charge negative.
They lose one electron which makes the atom negative.
They gain one electron to make a full outer shell (electron is negative).
Which of the following substances are make of molecules? (all numbers are subscript)
KCl
H2O
C2H6
MgO
CO2
NaNO3
Why can the structure of a metallic element like copper be represented by lots of spheres the same size packed closely together?
The atoms in copper are all the same size (and are spherical) and are packed tightly together (as a solid, in a giant structure)
Atoms are always represented as small circles the same size, solids are made of closely packed atoms and copper is a solid (at room temp).
Atoms are all metallic so are the same size and are packed closely together (as they attract each other).
Why do ionic compounds have giant structures?
Ions always have a free bond so attract more and more ions.
The forces between oppositely charged ions act in all directions, so ions are packed closely together in a regular arrangement.
Ions are very small so a crystal contains many ions.
Which is the correct dot and cross diagram for CH4? (4 is subscript)
Which is the correct diagram showing covalent bonds for H2O and 02?
H-O-H, O=O
H-O-H, O-O
H-H-O, O=O
Why does silicon (group 4) have a giant structure?
Group for elements can react and join to multiple atoms, this happens here and a giant structure is formed.
Silicon atoms join to others in al directions, so giant structure is formed.
They have four covalent bonds, so form to four other atoms, this continues until a giant structure is formed.
How are the atoms in sodium (metal) held together?
Atoms share electrons with each so all atoms have a full outer shell, this holds the atoms in place together. (forces between atoms are strong)
Outer electrons delocalise, leaving a lattice of positive ions, the delocalised electrons attract positive ions and hold them in position. (Electrostatic forces are strong)
Metallic atoms attract each other and are held together by strong magnetic forces.
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