Chapter 4- The chemistry of life (2) Flashcards
Are compounds heterogenous or homogenous?
Homogenous
What is a heterogeneous mixture?
A mixture that contains a substance in different phases, e.g, ice with water
What is a homogenous mixture?
A mixture that contains a substance in just one phase, e.g, just water
What are the 3 types of chemical bonds?
1- Ionic
2- Covalent
3- Hydrogen
How do electrons orbit?
In electron shells
What does each electron shell represent?
It represents a different energy level
In terms of potential energy, what happens to the potential energy as electrons go further away from the nucleus?
The further away from the nucleus, the more potential energy they have.
What is the valence shell?
Electrons in the outermost energy level that take part in chemical bonding
What happens when the outermost shell is full?
It is chemically inert- a chemical substance that is unreactive.
What elements are inert?
Noble gases
How do atoms with less than 8 electrons in their valence shell get a full outer shell?
Gain, lose or share electrons.
What ways can an atom have a full outer shell?
1- Ionic bonds
2- Covalent bonds
3- Hydrogen bonds
What is an ionic bond?
When two oppositely charged ions attract
How are electrons transferred?
Electrons can be donated from one atom to another.
Does an electron donor become positively charged or negatively charged?
Positively charged (cation)
Does an electron acceptor become positively or negatively charged?
Negatively charged (anion)
What happens as a result, when the two atoms have opposite charges (ionic bonding)?
The charges will attract and will chemically bond.
What is a covalent bond?
Where electrons are shared between two atoms.
What does a covalent bond allow?
It allows both atoms to stabilise.
What is the strongest bond and why?
Covalent bond because they are sharing an electron which neither atom wants to give up, so this ensures that the atoms remain strongly bonded to each other.
What types of bonds can covalent bonds be?
Single, double, and triple bonds.
In relation to chemistry, what are non-polar molecules?
Electrons that are shared equally between both atoms.
In relation to chemistry, what are polar molecules?
Molecules that don’t always allow equal share of an electron.
