Elements and Compounds pt 2 (lecture 4) Flashcards
The formation and function of molecule and ionic compounds depend
on chemical bonding between atoms
atoms with incomplete valance shells can
share or transfer valence electrons with certain other atoms
Chemical bonds are
the interactions that usually result in atoms staying close together, and are held by attractions
A covalent bond is
the sharing of a pair of valance electrons by 2 atoms
in a covalent bon, the shared electrons count as
part of each atoms valence shell
A molecule consist or
2 or more atoms of the same element held together by covalent bonds
A single covalent bond (single bond) is
the sharing of one pair of valence electrons
A double covalent bond (double bond) is
the sharing of 2 pairs of valence electrons
Covalent bonds can form between
atoms of the same element or atoms of different elements
A compound is
a combination of two or more different elements
An ionic bons is
a metal atom that loses 1 or more electrons to a nonmetal atom
A covalent bond is
when two nonmetal atoms share electrons
A hydrogen bon
attracts an electronegative atom electrostatistically
metallic bond
positive metal ions attract conducting electrons
Strong bonds
ionic bonds, covalent bond, coordinate bond, metallic bond
Weak bonds
hydrogen bond, van der walls interaction
Octet rule
an atom is most stable when there are eight electrons in its valence shell
Ions are atoms that
contain an uneven number of protons and electrons which results in an overall positive or negative charge
Cation are atoms that
contain positive charge. The positive charge is a result of the atom containing more protons than electrons
Anions are atoms that
contain a negative charge. The negative charge is a result of the atom containing more electrons than protons
An anion that has accepted two electrons has
a net charge of -2
The opposite changes of cations and anions exert
a moderately strong mutual attraction that keeps the atoms in close proximity forming an ionic bond
The ionic bond is an ongoing,
close association between ions of opposite charge
To determine the chemical formulas of ionic compounds, the following two conditions must be satisfied
- each ion must obey the octet rule for maximum stability
- ions will combine in a way that the overall ionic compound will be neutral in other words the charges of the ions must balance out
Covalent bonds involve
2 atoms, typically nonmetals, that share electron density to form strong bonding interaction
Covalent bonds include
single, double, triple bonds and are composed of sigma and pi bonding interactions where 2, 4, or 6 electrons are shared
Electronegativity is the
tendency of an atom or molecule to attract electrons and this form bonds
the strongest bonds in organisms are
covalent bonds that form a cells molecules
a hydrogen bond forms when a hydrogen atom
covalently bonds to one electronegativity atom is also attracted to another electronegative atom
in living cells, the electronegative partners are
usually oxygen or nitrogen atoms
if electrons are evenly distributed then
they may accumulate by chance in one part of a molecule
van der waals interactions are attractions between
molecules that are close together as a result of there charges
A molecules shape determined by
the positions of its atoms orbitals
in a covalent bond the s and p orbitals may
hybridize, creating specific molecular shapes
molecular sharpe determines how
biological molecules recognize and respond to one another
chemical reactions are
the making and breaking of chemical bonds
reactants are
the starting molecules of a chemical reaction
products are
the resulting molecules of a chemical reaction
all chemical reactions are
reversible products of the forward reaction to become reactants for the reverse reaction
chemical equilibrium is reached when
the forward and reverse reactions occur at the same time
at the equilibirum the
relative concentrations of reactants and products do not change
an elements properties depend
on the structure of its atoms
