Chapter 2: Chemical Basis Of Life Flashcards
what is an element?
a pure substance of 1 kind of atom
what is an atom?
the smallest functional unit of matter
what are the parts of an atom?
protons, neutrons, electrons
what are protons?
positive charge
what are neutrons?
no charge
what are electrons?
negative charge
how is an atom arranged?
the protons and neutrons are in the center of the nucleus. the electrons are arranged in orbitals around the nucleus. The first 2 electrons are in the first orbital and the rest are in the second
are the nucleus of a cell and atom different?
yes. the cell is a physical structure where the atoms is not
what makes up most of the weight of an atom?
the protons and neutrons because they both have an atomic mass of 1. The electrons have an atomic mass way less than 1 so they don’t weigh much
elements in the same column on the periodic table have similar…
properties
how are elements arranged?
by atomic number
what is the net charge of an atom?
it is zero or uncharged because the protons equal the electrons canceling each other.
what is atomic mass?
it is mainly based on #protons and neutrons
electrons are involved in what but have very little…
bonding
mass
what is electronegativity?
the ability of an atom to attract/ gain electrons
electronegativity increases which way on the periodic table?
left-right
when atoms lose an electron, what charge do they have?
positive charged ion
when atoms gain an electron, they have what charge?
a negative charged ion
noble gases are nonreactable because…
their outer most orbital is full
how do elements become the most stable?
have a full outer orbital or be completely empty
what are ions?
atoms that have gained or lost electrons
what are ions?
atoms that have gained or lost electrons
are ions charged particles?
yes. they can either be negative or positive
what do ions have to add up to in an ionic bond?
zero
when do opposites attract?
with ionic bonds
what are molecules?
made up of 2 or more atoms that are connected together by bonds. they can either be the same atom or different atoms (compound).
a molecule has a net charge of…
zero
ionic bonds are always charged and is between…
ions
what is a covalent bond?
when the electrons are shared between the atoms so there is no charge because there are no electrons.
why do they want to share a pair of electrons?
to become more stable
what is a type of covalent bond?
disulfide bonds
electrons are shared between two atoms
covalent bonds
hydrogen bonds are very…
weak
bond formed between a positively charged ion and a negatively charged ion
ionic bonds
what bond? Na+Cl-
C-C, C-H
ionic
covalent
what is a nonpolar covalent bond?
electrons are shared evenly between 2 atoms
what is a polar covalent bond ?
electrons are shared between 2 atoms, but they spend more time near one atom than the other. one end is partially positive and the other is negative
what type of atoms are electron hogs?
electronegative atoms
electrons spend more time near what?
the electronegative atoms than near other atoms
what is a polar molecule?
has a partial positive or partial negative charge at one end of molecule.
electronegative atoms in biological molecules are
O and N
what is a single bond?
a covalent bond that one pair of electrons is shared between atoms
what is a double bond?
a covalent bond that two pairs of electrons are shared between atoms
what is a triple bond?
a covalent bond where three pairs of electrons are shared between atoms
what is a disulfide bonds?
a covalent bond between two sulfur atoms S-S
what is a hydrogen bond?
a very weak bond that can break easily that is formed when a H atom is electrically attracted to an electronegative atom (O or N)
how many H bonds can there be in a molecule?
100s or 1000s
what are valence electrons?
the electrons in the outermost shell
what is ignored in calculations of atomic mass?
electrons
what are cations?
ions that have a net positive charge