Biology Week Two

Compound

Atoms joined by bonds

protons

positively charged subatomic particles

electrons

negatively charged subatomic particles

mass number

the protons and neutrons in an atom

atomic number

the number of protons in an atom

radioactive isotopes

isotopes that have unstable nuclei

Half-life

the time it takes for half of a radioactive isotope to decay

radiometric dating

a method used to calculate the age of fossils by measuring the amount of half-lives that have passed since the organism fossilized.

Energy

the capacity to cause change

potential energy

the energy that matter possesses due to its location

valence shells

the outermost energy shells of an electron

valence electrons

the electrons in an atom’s valence shell

orbital

the field around an atom in which electrons are likely to be found

covalent bonds

when two atoms share a pair of electrons

electronegativity

the force that pulls electrons to an atom

non-polar covalent bonds

covalent bonds where electrons are equally shared

polar covalent bonds

covalent bonds where electrons are unequally shared

kinetic energy

the energy of motion

thermal energy

total kinetic energy in a given mass

heat

average kinetic energy regardless of mass

calorie

the amount of heat it takes to raise the temperature of 1g of water by 1-degree Celsius

heat

the transfer of thermal energy

kilocalorie

1,000 calories

specific heat

the amount of water that must be lost for a substance to change its temperature by 1-degree Celsius

heat of vaporization

the quantity of heat that a liquid must absorb for 1g to vaporize

evaporative cooling

when the remain liquid cools down after some has evaporated

chemical equilibrium

when a chemical reaction and its inverse happen at the same rate

cohesion

the hydrogen bonding of water molecules

surface tension

a measure of how reactive the surface of a substance is

ions

atoms that have lost or gained electrons and are no longer neutral

cations

positively charged ions

anions

negatively charged ions

ionic compounds

compounds that are formed by ionic bonds

hydrogen bonds

bonds formed due to the polarity of two substances

van der walls interactions

interactions that occur when the electrons within an atom become unevenly distributed

chemical reactions

the making and breaking of chemical bonds

reactants

materials that trigger chemical reactions

products

the result of chemical reactions

solution

a completely homogenous mixture of two or more substances

solvent

the dissolving agent of a solution

solute

a substance being dissolved

aqueous solution

a solution dissolved in water

hydration shell

a sphere of water molecules that form around ions in an aqueous solution

hydrophilic

a substance that has an affinity for water

hydrophobic

a substance that repels water

molecular mass

the sum of the masses of all atoms in a molecule

mole

6.02×10²³ small particles

molarity

moles of a solute per liter

which substances are hydrophilic?

ionic and polar molecules

which substances are hydrophobic

non-ionic and non-polar molecules

hydrogen ion

a proton without an electron

hydroxide ion

a water molecule without a proton

hydronium ion

a water molecule with an extra proton

acids

a substance that increases the H⁺ concentration of a solution

bases

a substance that reduces the H⁺ concentration of a solution

What happens when the concentration of hydrogen ions in a solution increases?

the pH level decreases

what happens when the concentration of hydrogen ions in a solution decreases?

the pH level increases

buffers

substances that minimize changes to a solutions pH level

ocean acidification

the dissolution of CO₂ in oceans, lowering the pH level of the water

How do you find the total magnification of a microscope?

multiply the magnification of the objective lens by ten

compound microscope

a microscope that shines light through small specimens

stereoscope

a microscope used for observing large specimens