ch. 1: chemistry binds biology Flashcards
how old are the oldest fossils of life are estimated to be?
3.5 billion years old
describe the difference between an atom, a molecule and an element.
atom: smallest unit of an element
element: substance made up of atoms that have the same numbers of protons and can’t be broken down to simpler substances by chemical means
molecule: particle made up of two or more atoms that are chemically bonded
Know the usual number of bonds made by the following atoms
a. Sulfur (S)
b. Phosphorus (P)
c. Oxygen (O)
d. Nitrogen (N)
e. Carbon (C)
f. Hydrogen (H)
2
5
2
3
4
1
Know how to recognize an unlikely molecule. For example (other examples are open season on quiz), which of these is unlikely in nature (and for each one, why?):
O=O H-O-H H-C=C=O H=O
H-C=C=O because carbon has 4 electrons to give and requires 4 bonds, but only has 3 bonds out of the 4 needed to make it stable.
H=O because hydrogen only has one electron to give while there’s 2 covalent bonds connected to the hydrogen.
hydrogen bonds.
a. How are they formed?
b. What is their relative strength?
c. Give an example of each.
d. Which kind of bond gives water its many unique qualities?
e. Which type of bond is intramolecular and which type is intermolecular?
a: almost always partially positive, so it’s attracted to different partially negative pieces like (O&N)
b. weak
c. H2O
d. hydrogen bond because its partial charges make it maximally polar, which allows it to be unique among all solvents
e. intermolecular (weak)
covalent bonds.
a. How are they formed?
b. What is their relative strength?
c. Give an example of each.
d. Which type of bond is intramolecular and which type is intermolecular?
a. form when two or more atoms come together to share electrons to form a more stable outer electron shell
b. strong
c. O2
d. intramolecular (strong)
draw (with the correct number of covalent bonds) a polar molecule as well as a non-polar molecule, and describe what makes each polar or non-polar
Polar: S=C=O —> has a difference in electronegativity (sulfur has partially negative charge and oxygen has partially positive charge).
Nonpolar: CH4 —> carbon and hydrogen are electron neutral, their electron charges cancel each other out, and there’s no electron net charge/electrons are distributed evenly
Be able to name and describe three of the five unique characteristics of water.
cohesion: attraction between molecules of same substance
ice formation: when cooled enough to form solid, orientation of water molecules places them farther apart than they are in liquid form
high heat capacity: amount of hear needed to increase temperature of substances
high heat of vaporization: amount of energy required to transform a liquid to gas
universal solvent: most polar solvent, can dissolve widest range of substances
Be able to draw three water molecules as they would tend to exist near each other in nature.
oxygens have a partial negative charge and are attracted to the hydrogens partial positive charge
Nonpolar bonds
Bonds between atoms of same element
When C and H make a bond together
Polar bonds
When O or N form a bond with S,P,C, or H
Characteristic of water: Cohesion
Attraction between molecules of same substance
Characteristic of water: ice formation
When cooled enough to form solid, orientation of water molecules places them further apart than they are in liquid form
Characteristic of water: high heat capacity
Amount of heat needed to increase temperature of substances
Characteristic of water: high heat of vaporization
Amount of energy required to transform a liquid to gas
