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Biology 1 Ch 2

summer school
STUDY
PLAY
atom
smallest unit of matter that is unique to a particular element
proton
part of the atomic nucleus
positive charge
quantity is called the atomic number
neutron
part of the atomic nucleus
neutral charge
electron
negative charge
quantity is equal to the protons
move around the nucleus
charge
an electrical property that attracts or repels other subatomic particles
atomic number and mass number
_______ and ________ give us an idea of whether and how substances react
atomic number
number of protons in an atom and identifies that atom
mass number
total number of protons and neutrons in an atom
isotopes
atoms with the same number of protons but a different number of neutrons
12,13,14
most common isotope numbers
element
pure substances made of all the same kind of atom
periodic table
arrangement of elements based on their chemical properties
radio isotopes
unstable isotopes and tend to decay into more stable atoms
can be used in pet scans
subatomic particles
emitted when their nuclei break down
radioactive decay
process by which atoms of a radioisotope spontaneously emit energy and subatomic particles when their nucleus disintegrates
tracers
molecule with a detectable label attached
protons
electrons are attached to ______ but are repelled by other electrons
orbitals
like volumes of space around the atomic nucleus in which electrons are likely to be at any instant
contains one of 2 electrons
1,2
the shell closest to the nucleus has ___ orbital(s) holding a maximum of __ electrons
4,8
the second shell can have __ orbitals with 2 electrons each for a total of ___ electrons
unfield
atoms with _____ orbitals in their outermost shell tend to be reactive with other atoms
chemical bond
a union between the electron structures of atoms
molecule
bonded unit of 2 or more (same or different) atoms
compound
substance in which the relative percentages of 2 or more elements never vary
mixture
in a ______, 2 or more elements simply intermingle in proportions that can vary
ion
when an atom loses or gains one of more electrons, it becomes a positively or negatively charged ______
ionic bond
positive and negative charged ions are linked by mutual attraction of opposite charges
covalent bond
holds together two atoms that share one or more pairs of electrons
single bond
2 atoms sharing one pair of electrons
double bond
2 atoms sharing two pairs of electrons
triple bond
2 atoms sharing 3 pairs of electrons
nonpolar covalent bond
atoms share electrons equally
polar covalent bond
slight difference in charge between the 2 poles of the bond
ex: water
hydrogen bond
atom of a molecule interacts weakly with a hydrogen atom already taking part in a polar covalent bond
polar
water is a _____ molecule because of a slightly negative charge at the oxygen end and a slightly positive charge at the hydrogen end
hydrogen bonds
water molecules can form ______ with each other
solvent properties
the _______ of water are greatest with respect to polar molecules, with which they interact
solvent
usually liquids and can dissolve other substances
solutes
substances that are dissolved
hydrophilic
polar substance that is water loving
hydrophobic
nonpolar substance that is water dreading
cohesion
capacity to resist rupturing
especially important in pulling water through plants
surface tension
hydrogen bonding of water molecules provides cohesion which imparts ______
pH
measure of the # of hydrogen ions in a solution
acidic
0 to 7 on pH scale
base
7 to 14 on pH scale
acid
substance that releases hydrogen ions in a solution
bases
substances that releases ions that can combine with hydrogen ions
salt
ionic compound formed when an acid reacts with a base
bicarbonate
one of the body's major buffers