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biology
The study of life
organism
Any living thing
matter
anything that takes up space and has mass
Elements
any substance that cannot be broken down into simpler substances by chemical reactions
Compound
a substance consisting of two or more elements in a fixed ratio
trace elements
required by an organism in only minute quantities
Elemental deficiencies
inadequate amounts of an essential nutrient causing a health problem
atoms
smallest unit of matter
subatomic particles
protons, neutrons, electrons
Proton
positive charge, in nucleus
neutron
no charge, in nucleus
Electrons
negative charge, have potential energy
,atomic nucleus
consists of protons and neutrons
electron cloud
region around the nucleus that electrons occupy
daltons (Da)
1 Da = mass of 1 proton/neutron
electron shells
An energy level representing the distance of an electron from the nucleus of an atom.
atomic number
number of protons
atomic mass
Number of protons and neutrons
Isotopes
Atoms with the same number of protons but different numbers of neutrons
unstable/radioactive isotopes
nucleus decays spontaneously and gives off particles and energy
Electron's state of potential energy is called
energy level or electron shell
the more distant an electron is from the nucleus of an atom, the greater its ...
potential energy
1st electron shell
max of 2 electrons
2nd electron shell
max of 8 electrons
3rd electron shell
max of 8 electrons
valence electrons
electrons in the outermost shell
Move toward a full valence shell by
, - adding electrons to the outer shell
- losing electrons
- sharing electrons in the outer shell
chemical bonds
when two atoms share valence electrons resulting in them being held together by this attraction
fewer valence electrons =
less stable and more likely to react
covalent bonds
strong bonds resulting from the sharing of electrons
nonpolar
equal sharing of electrons
polar
not equal sharing of electrons
ionic bonds
bonds resulting from loss and gain of electrons; more EN atom strips a valence electron from the other
atom
hydrogen bonds
weak bonds formed between a hydrogen atom and a polar compound
van der Waals force
very weak bonds resulting from transient shifting of charges created by the constant movement of
electrons
structural formula
H-H
molecular formula
H2
Lewis dot (shows valence electron distribution)
H:H
single bond
covalent bond; sharing of one pair of valence electrons
double bond