Intro to Chem Exam 3

when two or more elements combine together
Chemical bonds
the atoms of compounds are connected by
is formed when an element has eight valence electrons
Atom with an octet is
exception for stable atoms and octets is
He which is stable with 2 electrons because the n=1 energy level is completely filled
octet rule
atoms form compounds by gaining, loosing,or sharing electrons to acquire an octet of eight valence electrons.
Two types of compounds
ionic compounds
covalent compounds
ionic compounds
between a metal and a nonmetal
covalent compounds
between two or more nonmetals
covalent compounds are formed by the
sharing of valence electrons between atoms of nonmetals
two shared electrons a (shared pair) form a
single covalent bond
with covalent bonds
each atom acquires an octet
how many atoms in the prefix mono
how many atoms in the prefix di
how many atoms in the prefix tri
how many atoms in the prefix tetra
how many atoms in the prefix penta
how many atoms in the prefix hexa
how many atoms in the prefix hepta
how many atoms in the prefix octa
how many atoms in the prefix nona
how many atoms in the prefix deca
how many elements are diatomic elements
diatomic elements are
elements of the same sort which share a covalent bond
Ionic compounds
are formed between a metal and nonmetal
Ionic compounds are formed by
completely transferring all valence electrons from the metal to the nonmetal
Cation are formed in ionic compounds because
the metal has given the nonmetal its valence electrons leaving more protons then electrons
Cations are charged
Nonmetals in ionic compounds form an
anion ion which is negative because it now has more electrons then neutrons
Electrostatic forces
ions with opposite charges are held together by this
Positive ions
metals ionization energy
is low meaning it is easy to remove electrons
Metals form positive ions or cations by
loosing all of their valence electrons
Negative ions are known as
a negative ion is formed by
gaining electrons
cation -metal ion is named
(the name of the element) ion
Anion- nonmetal ion is named by
changing the end of the name of the element to ide
Anions in group 5A have
3- charge
Anions in group 6A have
2- charge
Anions in group 7A have
1- charge
Noble gases can’t from anions because
there octets are full
ionic compounds
are neutral
Name all the Diatomic Molecules
Name the Ionic Compound NaCl
sodium chloride
Name the Ionic Compound K2S
potassium sulfide
Name the Ionic Compound MgO
magnesium oxide
calcium iodide
Transition Metals form
two or more positive ions
Exception elements to transition metals
Zinc, Cadmium, and Silver only make one ion
Polyatomic Ions
is a group of covalently bonded atoms
Polyatomic Ions charges
an overall ionic charge
Polyatomic ions can be
an anion (-) or cation +
More oxygen means
less oxygen means
in a chemical change
reacting substances form new substances with different compositions and properties a chemical reaction occurs
a chemical change produces
one or more new substances
in a chemical change the composition
of one or more substances is changed
in a chemical change old bonds
are broken and new bonds are formed
Atoms in the reacting substances are
rearranged to form one or more different substances
chemical reactions are represented
by chemical equations
Chemical equations are written with
the reactants on the right and the products on the right
this symbol (+) means
separates two or more formulas
this symbol means ————->
Reacts to form products
this symbol (triangle) means
reactants are heated
this symbol (s) means
this symbol (l) means
this symbol (g) means
this symbol (aq) means
combination reactions are
two or more elements or simple compounds form one product
Decomposition reactions
one substance splits into two or more simpler substances
Single replacement reactions
Free element takes the place of a different element in a reacting compound
Double replacement reactions
the positive ions or cations of compounds exchange places
Combustion Reactions
a compound or element such as carbon reacts with oxygen EX fuel is burned and oxygen is produce
In a balanced equation
atoms are not gained or lost
total number of atoms of each element is the same in the reactants and in the products
A buffer is
substance that maintains a constant pH
The resists
a change in the pH upon the addition of a acid or base
Buffers neutralize
a small amount of the added acid or base
The human body contains buffer
buffers that help a pH of 7.4 in the blood
A buffer solution contains
a weak acid and its salt
A buffer may also contain
a weak base and its salt
A buffer typically has equal
concentrations of a weak acid (or base) and its salt
A neutralization reaction
an acid such as HCI and a base such as NaOH react with each other
The H+ from the acid and the OH- from The H+ from the acid and the OH- from the base combine to form
water as a product
In the equation for neutralization
an acid and a base produce a salt and water
Acids react with some metals
to give a salt and hydrogen gas
Acids react with carbonates and bicarbonates
to give carbonic acid and a salt
Carbonic acid further breaks down
to carbon dioxide and water
The pH scale is used
to indicate the acidity of a solution
The pH scale range is from
a neutral solution has a pH
of 7
An acidic solution has a pH
less then 7
A base solution has a pH
greater then 7
Strong bases completely ionizes into
OH- in the water
bases produce
OH- Ions in water
Most bases are from groups
1 2
Bases taste
bases neutralize
Acids produce
H+ ions in water
Acids have a
sour taste
acids neutralize
Acids turn litmus
to red
bases turn litmus paper
Strong acids completely ionizes
into H+ in water