Biology 161 - Exam 2 Vocabulary - Chemistry of Biology

Atom

smallest unit of matter holding properties of an element. Cannot be further divided without releasing charged particles

Proton

mass of 1 and a positive charge

Electron

mass is negligible and a negative charge

Neutron

mass of 1 and no charge

Nucleus

center of an atom, where the protons and neutrons are located

Atomic Number

number of protons

Electron Shells

energy levels around the nucleus

Valence Shell

the outermost shell around the nucleus of the atom

Valence electrons

determine an atom’s chemical properties and how it will behave in chemical reactions

Electronegativity

the tendency of an atom to attract electrons

Covalent Bond

involve the sharing of electrons. the atoms move close together and share the electron pair

Ionic Bond

involve the transfer of electrons from one atom’s valence shell to another valence shell

Hydrogen Bond

occurs between H with a partial positive charge and another atom with a partial negative charge

Hydrophilic

substances that interact with water

Hydrophobic

substances unable to interact with water

Hydrophobic Interactions

non-polar molecules will tend to associate with each other when in a polar solvent like water

Van Der Waals Interactions

interactions between nearby non-polar molecules, when a random slight shift in the electron cloud causes slight partial charges that can then interact

Non-Polar Bonds

equal sharing of electrons when 2 atoms have similar electronegativity, no charges present

Polar Bonds

unequal sharing of electrons, occurs when 2 atoms differ in electronegativity, partial charges exist around the atoms

Solution

single-phase mixture of two or more substances

Solvent

substance that dissolves another substance

Solute

substance that dissolves within another substance

Molarity

Moles of Solute/Liters of Solution

Mole

a unit to measure the number of particles of a particular substance (atoms or molecules)

Molar Mass

refers to the weight of a mole of a particular substance. give in grams per mole

Avogadro’s Number

6.022×10²³ atoms

Dilution

Adding water or another liquid to reduce the molarity of a solution

H+ ions

protons

pH

a specific measure of the number of H+ in a solution

Acid

proton (H+) donor. compound that releases a proton in an acid-base chemical reaction

Base

proton (H+) acceptor