bio lecture 2 Flashcards
matter
anything that takes up space and has mass
element
a substance that cannot be broken down to other substances by chemical reactions
compound
a substance consisting of two or more elements in a fixed ratio
Neutrons
no electrical charge
atom
is the smallest unit of matter that still retains the properties of an element
Protons
positive charge
Electrons
negative charge: form a ”cloud” around the nucleus
atomic number
is the number of protons in its nucleus
mass number
protons + neutrons in the nucleus
Atomic mass
the total mass of an atom, which is made up of protons, neutrons, and electrons
Isotopes
atoms of the same element that contain an identical number of protons, but a different number of neutrons
Radioactive isotopes
atoms that contain an unstable combination of neutrons and protons, or excess energy in their nucleus.
potential energy
the energy that an object stores due to its position or internal structure, and has the ability to do work
Energy
the capacity to cause change
a group of electrons in an atom that are grouped around the nucleus according to their energy
Valence electrons
are those that occupy the valence shell (FIX LATER)
single bond
one pair of electrons shared, indicated by a single line between the atoms: H—H
Double bond
2 pairs of electrons shared, indicated by a double line between atoms
0==0
Covalent bond
atom shares electron with each other
Electronegativity
is an atom’s attraction for the electrons of a covalent bond
nonpolar covalent bond
atoms share the electrons equally
polar covalent bond
one atom is more electronegative; atoms do not share the electron equally. causes a partial positive or negative charge for each atom or molecule
ionic bond
attractions between positive charge ion and a negative charge ion.
cation
a positively charged ion
anion
a negatively charged ion
Hydrogen Bonds
forms when the hydrogen plus charge atom is attracted to a negative charge atom such as oxygen or nitrogen atom
van der Waals interactions
occur only when atoms and molecules are very close together
Chemical reactions
the making and breaking of chemical bonds
reactants
the starting molecules of a chemical reaction
products
The final molecules of a chemical reaction
polar molecules
a molecule in which one end of the molecule is slightly positive, while the other end is slightly negative.
cohesion
attraction of molecules to the same kind
surface tension
how hard it is to break the surface of a liquid
adhesion
the attraction between 2 different substances
Kinetic energy
the energy of motion
Thermal energy
a measure of the total amount of kinetic energy due to molecular motion
Temperature
represents the average kinetic energy of molecules
Specific heat
amount of heat must be absorbed/lost for 1 g of substance to change its temp by 1C
Heat of vaporization
is the heat a liquid must absorb for 1 g to be converted to gas
solution
a homogeneous mixture of one or more solutes dissolved in a solvent.
solvent
is the dissolving agent of a solution
solute
the substance that is dissolved
aqueous solution
one in which water is the solvent
hydrophilic
ones agility to interact with water. ex: mix or dissolve
hydrophobic
can’t interact with water tending to repel water
