Chapter 1 - Review Flashcards
Elements
2 or more of the same type of atoms bonded together
Matter
- anything that takes up space or weight
- found in 3 phases: solid, liquid, gas
- made up of elements
Atom
Smallest unit of matter
Ex. Carbon
Molecule
2 or more atoms bonded together (can be same type of atoms or different)
Ex. C2
Compound
2 or more different types of elements bonded together
Ex. H20
Sub-atomic particles
- protons
- neutrons
- electrons
Protons
- inside nucleus
- positive charge
- weigh 1 atomic mass unit
Neutrons
- inside nucleus
- no charge
- weigh 1 atomic mass unit
Electrons
- move around nucleus in orbitals
- negative charge
- weigh nothing
Atomic number
Number of protons (which is equal to the number of electrons)
Atomic mass
Number of protons and neutrons
Isotopes
Atoms of the same element with a different mass because they have a different number of neutrons
Ex. Carbon has 3 isotopes
Tracers
Radioactive isotopes used to follow biological processes/pathways in living organisms
Ex. Dye in bloodstream to check for clots
Heavy isotope
An atom with more neutrons
Which 4 elements are the most common in the human body?
Oxygen, carbon, hydrogen, nitrogen
Why does a neutral atom have no net charge?
Because the protons and electrons cancel each other out
What determines if an atom will gain, lose, or share electrons?
The number of electrons in its shell
As the number of neutrons increases, the atomic number _______ and the atomic mass ________
- stays the same
- increases
How are electrons held in orbit?
By their attraction to protons
Octet rule
- 1st orbit holds a maximum of 2 electrons
- the rest hold a maximum of 8
Why do atoms bond?
To create a stable outer unit
Chemical bonds
Form when electrons are gained, lost, or shared
Ionic bond
- between metals & non-metals
- electrons leave one atom and attach to the new atom
- lose an e: positively charged ion
- gain and e: negatively charged ion
- ions are held together by a weak electromagnetic force
Covalent bond
- between 2 non-metals
- electrons shared, not transferred
- non-polar bond: electrons shared equally because atoms are similar in size
- polar bond: difference in atom sizes causes one to have more pull on the shared election, resulting in a difference in charge between the 2 poles of the molecule (ex water)
Hydrogen bond
- gives structure to liquid water
- stabilizes nucleic acids & other large molecules
- drawn as a dotted line because they are so weak
Electron-dot/Lewis dot formula
- shows only the electrons in the outer orbital
- electrons shown by dots
- place 1 dot on each quadrant, then double up
Structural formula
- bonds shown by straight lines
- 1 line = 1 pair of shared electrons
Molecular formula
- shows only the amount of each type of atom in the molecule
- does not indicate any bonds
Ex. CH4
Empirical formula
Show lowest ratio of atoms (kind of like reducing the molecular formula)
Ex. C2H6 in molecular = CH3 in empirical
More than 1 bond…
- atoms may share more than just 1 pair of electrons
- if 2 pairs are shared: double bond
- if 3 pairs are shared: triple bond
- double & triple bonds are much stronger than single bonds
Chemical make-up of water
- 2 hydrogen atoms joined to the oxygen atom by a single covalent bond
- polar molecule
Properties of water
- cohesion
- surface tension
- specific heat
- evaporative cooling
- solvent/dissolving agent
Cohesion
Water molecules are bonded together by hydrogen bonds, giving water more structure than most other liquids
Surface tension
Water has a great surface tension - bugs and lizards can walk across it without breaking the surface tension
Specific heat
- Has high specific heat
(1 calorie per gram per degree Celsius) - takes a long time to heat up due to the number of h-bonds
- helps protect living systems from rapid temperature changes & maintain a normal internal environment
Evaporative cooling
When the hottest molecules leave, the surface of the liquid that remains cools down
Solvent
- Water is a solvent/dissolving agent…aka an aqueous solution
- can dissolve polar molecules (ex salt & sugar)
Hydrophilic
A substance with an affinity to water
Ex. Cotton, which absorbs water
Hydrophobic
A substance that repels water
Ex. Oil
Water in the human body
- human body is approximately 65% water
- as you get older, the amount of water reduces
Effects of dehydration
- fuzzy short-term memory
- trouble with basic math
- problems focusing on small print
Water’s uses in the body
- lubricant
- base for saliva
- forms fluids surrounding joints
- regulates body temperature
- prevents constipation
- regulates metabolism
Dissociation
Water molecules dissociate (break apart) to produce hydrogen ions (H+) and hydroxide ions (OH-)
How to determine acidity vs bascity
Determined by number of free H or OH ions
Acids
Molecules that dissociate in water to release H
Bases
Either take up H or release OH
Oxidized
When an atom loses an electron or when a molecule loses a hydrogen atom
Reduced
When an atom gains an electron or molecule gains a hydrogen atom
pH
- indicates acidity/basicity of a solution
- scale ranges from 0-14
- each step up or down the scale is equal to a jump in 10x the strength
Ex. Acid of pH 4 is 100x stronger than acid of pH 6
Biological importance of pH regulation
metabolic reactions, molecular structure, and toxicity of molecules depend on pH
Neutralization
- When an equally strong acid & base react
- produces water & salt
Ex. HCl + NaOH –> NaCl + H2O
Buffers
Chemicals that resist pH changes by taking up excess H or OH
Ex. Buffering of blood by carbonic acid & bicarbonate ion
When hydrogen is added to blood:
H + HCO3 –> H2CO3
Buffering blood with hydroxide ions
Water is formed
Ex. **OH + H2CO3 –> HCO3 + H2O
If a buffer is added to an acidic solution, the pH will ______
Increase
If a buffer is added to a basic solution, the pH will ________
Decrease
