Biology Notes

What makes up 96% of matter?

Hydrogen, carbon, nitrogen, oxygen

What determines function?

Shape dictates how a molecule behaves

What is mass number?

Protons plus neutrons in nucleus

What is atomic number?

Protons

How is atomic mass measured?

In special units called the dalton (Da)

What are isotopes?

Forms of an element with different # neutrons

What changes in an isotope?

The neutron, which means mass number changes

What does a radioactive isotope indicate?

It is unstable

What is the atomic weight?

The average of all naturally occurring isotopes in an element

What to know about orbitals?

Can hold up to two electrons, are the “houses” on the electron shell “road”. They will each have 1 electron before having pairs.

What is the outermost shell called?

Valance shell, # of unpaired electrons is called the valence

How many electrons are in a filled valence shell?

8

What is a covalent bond?

Two atoms sharing electrons

What is electronegativity?

Electrons are not shared equally when atoms of different elements are bonded together in a compound.

What is a polar versus non polar covalent bond?

Polar is when electrons are shared unequally versus non polar is when they are shared equally

What situation means high electronegativity?

More protons and less shells

What are ionic bonds

Formed when electrons fully transfer from one to the other.

What are positive versus negative ions called?

Positive cations versus negative anions

What are ways to represent molecules?

Molecular formula, structural formula, ball-and-stick model, space-filling model

Where did the Earth form?

In aqueous environments

What is water good at?

Being a solvent, meaning an agent for dissolving substances into a solution

What is water’s most dense form?

Liquid, the molecules have kinetic energy to break and reform in liquid but in ice have rigid state which is why ice floats

What is specific heat?

Amount of energy required to raise temperature of 1 gram by 1 degree C.

What is a good equation for specific heat?

As polarity rises, hydrogen bonds rise, and more energy is needed.

How do chemical reactions work?

The reactant (initial) on the left and product (resulting) on the right work to have an equal number of atoms in each element

What is chemical equilibrium?

There is a constant concentration that is trying to become equal

What are ions?

Substances that have an electric charge because of gaining or losing electrons

What is molecular weight?

The sum of the atomic weights of all atoms in a molecule

What is Molarity?

The number of moles in solute present per liter of solution

What molecules release versus accept protons?

Basic accepts, acids release

Where were chemical reactions started that spurred chemical evolution?

They started in the atmosphere and in deep-sea hydrothermal vents

What is endothermic verses exothermic

Liquid to gas is endothermic and gas to liquid is exothermic

What is energy?

The capacity to do work or supply heat

What does the transfer of energy look like?

Heat

1st law of thermodynamics

Energy can only be transferred or transformed not destroyed

2nd law of therodynamics

Entropy rises when both system and environment are accounted for

Miller’s Spark Discharge Experiment

Simulated early Earth by adding electrodes to methane, ammonia, hydrogen, etc. and with water