Chemical Bonding Flashcards
What is a compound?
A substance that is made up of two or more different elements, chemically combined.
How are atoms held together?
By chemical bonds
Describe noble gases
They contain 8 electrons in their outer shell and are generally unreactive.
What are the uses of helium?
- Airships because it is not flammable.
- Balloons because it is lighter than air.
What are the uses of argon?
Used in lightbulbs to stop imploding.
What is the octet rule?
When bonding occurs, atoms tend to reach an electron arrangement with 8 electrons in the outer shell.
What are the limitations of the octet rule?
- Hydrogen
- Lithium
- Transition Elements
What is a valency?
It is the number of bonds an atom makes when it reacts.
What is a transition metal?
It is a metal that forms at least one ion with a particularly filled ‘d’ sublevel.
List three facts about transition metals which could be good to know.
- They have a variable valency.
- They form coloured compounds
- They are used mainly as catalysts.
What are the two exceptions of transition metals?
- Zinc (Zn)
- Scandium (Sc)
What is ionic bonding?
It is the transfer of electrons.
What is an ion?
A charged atom/group of atoms.
What is the charge of a cation?
Positive
What is the charge of an anion?
Negative
List the chemical equation of how cations formed.
Na —> (Na+) + (e-)
Ca —> (Ca2+) + (2e-)
List the chemical equation of how anions formed.
Cl- —> (Cl) + (e-)
O2- —> (O) + (2e-)
Define ionic compounds.
It is the force of attraction between oppositely charged ions in a compound.
What are the characteristics of ionic substances?
- Strong forces between the ions mean it is very hard to break up due to the lattice structure.
- Cannot conduct electricity when solid but can when dissolved in water.
- Most dissolvable in water.
With ionic substances, comment on the:
- boiling and melting points.
- the state that it’s in at room temperature.
Both boiling and melting points are high and it is solid at room temperature.
Name two everyday examples of ionic substances.
- Table salt (Sodium Chloride) (NaCl)
- Floridation (Sodium Floride) (NaF)
When is a covalent bond formed?
When atoms share electrons.
What is an example of a single covalent bond?
H2
What is an example of a double covalent bond?
O2
What is an example of a triple covalent bond?
N2
What are bonding pairs?
They have shared electron pairs that form covalent bonds.
What are lone pairs?
They are electron pairs that aren’t involved in covalent bonds.
What happens to the orbitals in a covalent bond?
The orbitals overlap each other