Chemistry of Life Study Guide Flashcards
Molecule vs. Compound
A molecule is two or more atoms bonded together. A compound is two or more different atoms bonded together. All compounds are molecules but not all molecules are compounds.
What are the three subatomic particles? What are their charges and where are they located?
Protons have a positive charge (in nucleus). Neutrons have a neutral charge (in nucleus). Electrons have a negative charge (cloud outside the nucleus).
Atomic Number
The number of protons in an atom of the element. In a neutral atom, it is also equal to the amount of electrons.
Atomic Mass
Average mass of all the atoms of the element. It’s a decimal number.
Mass Number
The sum of the number of protons and neutrons in a single atom. It’s a whole number.
What are the five properties of water?
- Cohesion. The attraction between molecules of water (hydrogen bonds). Causes high surface tension. Surface tension is a measure of how difficult it is to break the surface of a liquid.
- Adhesion. The type of attraction that happens between DIFFERENT molecules. Forms stronger bonds than cohesion. (Ex. capillary action - water moves against gravity)
- High Specific Heat. The temperature of water does not increase or decrease easily.
- Less Dense as a Solid. Solid water (ice) is less dense than liquid water. Meaning, ice floats and life can exist under the frozen surface of lakes/polar seas.
- Water is a Terrific Solvent! It can dissolve many things.
Why is water’s high specific heat beneficial? (Three Reasons)
It helps to regulate cell temperatures in organisms. Allows life to live in water (the temperature doesn’t fluctuate very much). Moderates Earth’s climate by buffering large fluctuations in temperature.
Hydrophilic
Water “loving”. Dissolves in water.
Hydrophobic
Water “fearing”. Does not dissolve in water.
What is electronegativity? What is it affected by? What happens when the electronegativity is higher?
Electronegativity is the tendency for an atom to attract shared electrons when forming a chemical bond. An atom’s electronegativity is affected by both its atomic number and the distance the valence electrons are from the nucleus. The higher the associated electronegativity, the more an atom attracts electrons.
Polar Molecule
In a polar molecule there is an unequal distribution of charge. One side is more positive and one is more negative. It dissolves in water
Nonpolar Molecule
No separation of charges, so no positive and negative poles are formed. Does not dissolve in water.
Isotope
An element with the same number of protons but a different number of neutrons. It is written using the mass number.
What is an Ion? What are the two types?
An Ion is a charged atom which differs in the number of electrons. Anions are negatively charged, meaning they have more electrons than protons (3-). Cations are positively charged, meaning they have more protons (3+).
What overall charge does the nucleus have?
Positive
