Atomic Structure and Covalent Bonding Flashcards
What is meant by the term Isotope.
An isotope is an atom with the same atomic number but different mass number.
What is meant by the term relative atomic Mass?
The relative atomic mass is the calculation used to find the weighted average mass between two or more isotopes, using the abundance percentage X the atomic number.
What is meant by the term covalent bond?
A covalent bond is the force of attraction between a shared pair of electrons and nuclei.
What are simple Molecular structures?
Covalently bonded molecules with weak intermolecular forces.
Give two examples of substances with Giant covalent structures?
Diamond and Graphite
Why do Giant covalent substances have high melting points?
They have a lot of very strong covalent bonds and it takes a huge amount of energy to break the bonds.
Explain in terms of its structure why graphite is used as a lubricant?
Graphite is made up of layers of carbon. Graphite is very slippery and the layers separate very easily because of weak forces of attraction. As it is slippery it makes a good lubricant.
In terms of its structure why is diamond used in cutting?
Diamond is made up of lots of covalent bonds which require a lot of energy to break. it is a giant interlocking molecular structure and is an very hard substance.
What is an atom?
A single particle (no charge)
What is a molecule?
two or more atoms chemically joined together
what is an ion?
a charged particle
What is an element?
A collection of atoms or molecules of the same kind.
what is a compound?
Two or more elements chemically combined.
what is a mixture?
different elements or compounds mixed together.
what is the structure of an atom?
the atom is made up of a central nucleus surrounded by electron shells.
What are the three sub-atomic particles an atom is made up of?
Protons neutrons electrons
What is an atomic number?
Is the number of protons in the nucleus of an atom
What is the mass number?
the sum of the number of protons and neutrons in the nucleus of the atom.
Nuetral atoms have what kind of charge?
zero charge
What is a charged atom called?
an ion
If an electron is added to a neutral atom what kind of charge does it gain?
It becomes negatively charged.
A covalent bond is usually formed between what?
Two non-metals
the sharing of electrons results in what?
both atoms having a complete outer shell of electrons.
what does a full shell mean?
the arrangement is particularly stable
covalent bonds are?
very strong and require a lot of energy to break.
Covalently substances can form two types of structures:
Simple molecular giant covalent
what is a molecule?
A small group of atoms joined by covalent bonds
3 molecular elements include:
oxygen, hydrogen, nitrogen
3 molecular compounds include:
Carbon Dioxide, water, methene
Properties of simple molecular substances include:
They can be solids, liquids or gases, they have low melting and boiling points
why do simple molecular substances have low melting points?
-Weak forces of attraction -wear intermolecular forces do not require a lot of energy to break
Giant covalent substances include:
diamond (carbon atoms) graphite (carbon atoms) sand (silicon dioxide)
diamond has what kind of melting points and why?
very high melting points because it has very strong covalent bonds
In what way is Graphite arranged?
In layers of hexagons-strong covalent bonds join atoms together. layers need a lot of energy to break.
What is between the layers in graphite?
Weak forces of attraction
Does Graphite conduct electricity and why?
Yes, because it has delocalised electrons which can carry a current.
How is sand (silicon dioxide) structured?
Each silicon atom is covalently bonded to 4 oxygen atoms and each oxygen is covalently bonded to two silicon atoms. No delocalised electrons
Describe the structure of diamon
describe the structure of Graphite?
Describe the structure of sand
