Topic 2-bonding Flashcards
describe metals and nonmetals and explain the differences between
them on the basis of their characteristic physical and chemical properties
Metals = elements that react to form positive ions.
Majority of elements are metals.
Found to the left and towards the bottom of the periodic table
they lose electron(s) in order to form positive ions
metals are typically shiny, good electrical conductors, are dense and have
high melting points
Non-metals = elements that react to form negative ions.
Found towards the right and top of the periodic table
they gain electron(s) in order to form these negative ions
nonmetals are typically dull in appearance, poor electrical conductors,
aren’t dense and have low melting points
explain how the position of an element in the periodic table is related
to the arrangement of electrons in its atoms and hence to its atomic
number
Elements are arranged in order of atomic (proton) number and so that elements
with similar properties are in columns, known as groups.
Elements in the same periodic group have the same amount of electrons in their
outer shell, which gives them similar chemical properties.
Group number refers to the number of outer shell electrons
Period number refers to the number of shells of electrons
describe and compare the nature and arrangement of chemical bonds in ionic bonding
lonic compounds:
ionic bonding
formed between a metal + non-metal: electrons in the outer shell of the
metal atom are transferred to the nonmetal
Held together by strong electrostatic forces of attraction between
oppositely charged ions
An example is sodium chloride (salt):
Na+ (small blue particles) and C|- (larger green ones)
lonic compounds have regular structures (giant ionic lattices) in which there are strong They have high melting and boiling points, because a lot of energy is required to break the many strong bonds.
When melted or dissolved in water, ionic compounds conduct electricity
because the ions are free to move and carry current.
Polymers
covalent bonding (look at simple molecules)
Have very large molecules
Atoms in the polymer molecules are linked to other atoms by strong
covalent bonds
Intermolecular forces between polymer molecules are relatively strong
and so these substances are solids at room temperature
Giant covalent structures
covalent bonding
Substances that consist of giant covalent structures are solids with very high melting points.
All of the atoms in these structures are linked to other atoms by
strong covalent bonds.
These bonds must be overcome to melt or boil these substances.
Metals
metallic bonding
Metals consist of giant structures of atoms arranged in a regular pattern.
The electrons in the outer shell of metal atoms are delocalised and so are free to move through the whole structure.
The sharing of delocalised electrons gives rise to strong metallic bonds.
Metals have giant structures of atoms with strong metallic bonding.
Therefore, most metals have high melting and boiling points.
They can conduct heat and electricity because of the delocalised electrons in their structures.
The layers of atoms in metals are able to slide over each other, so
metals can be bent and shaped.
explain chemical bonding in terms of electrostatic forces and the
transfer or sharing of electrons
ionic bonds: electrostatic attraction between oppositely charged ions, formed by the transfer of electrons
covalent bonds: electrostatic attraction between a shared pair of electrons
metallic bonds: electrostatic attraction between positive metal ions and the sea of delocalised electrons
