Transcript Chapter 4 The Structure of Matter

Chapter 4 The Structure
of Matter
• I. 4.1 Compounds and Molecules
• II. 4.2 Ionic and Covalent
Bonding
• III. 4.3 Compound Names and
Formulas
• IV. 4.4 Organic Chemistry
I. 4.1 Compounds and
Molecules
• A. What are Compounds?
• 1. Chemical bonds are the
attractive force that holds atoms
or ions together in compounds.
• 2. Compounds always have the
same chemical formula
• a.
• b.
• c.
• d.
• e.
com - with, together, jointly
pound - put, position
water H20
table sugar C12H22O11
salt NaCl
• B. A chemical formula shows
the types and numbers of atoms
or ions making up the simplest
unit of the compound.
• 1. There is a difference between
CO and CO2
• a. each is made up of C and O but one
has 2 O atoms
• 2. The same for H2O and H2O2
(hydrogen peroxide)
• 3. Compounds are always made up
of the same elements in the same
proportion.
• 4. The formula can tell us what
atoms a compound is made of but
does not reveal how they are
connected.
• 5. The chemical structure show
the arrangement of bonded atoms
or ions within a substance.
• a. Two terms are used to specify the
relative positions of atoms to each
other in a compound.
− (1) Bond length - gives the distance
between the two nuclei of the atoms
− (2) Bond angles tell how these atoms are
oriented when you have three or more
atoms in the compound.
• C. Models of compounds can
help us to see a compounds
structure.
• 1. Ball and stick
• a. the ball represents the atom
• b. the stick represents the bonds.
• c. hard to see the relative size of the
atoms
• 2. Structural formula use the
chemical symbol to represent the
atoms
• a. hard to see the relative size of the
atoms
• 3. Space filled models
• a. shows the relative size of the atoms
• b. H2O - hydrogen atoms taking up
less space than the oxygen atoms
• c. hard to see the bond angle and
lengths
• D. Structure effects properties
• 1. Some compounds form crystals
when the chemical bonding is
repeated over and over again to
form very strong structures.
• a. Quartz SiO2
− (1) bond angle 109.5o
− (2) makes a very strong, rigid structure
− (3) rocks made of quartz are very hard and
inflexible
− (4) the reason why the melting and boiling
points of quartz is so high
– (a) melting point 1700oC
– (b) boiling point 2230oC
• 2. Some networks are made of
bonded ions
• a. NaCl crystal is made of tightly
packed Na+ ions and Cl+ ions
• b. this strong attraction produced a
high melting and boiling point
− (1) melting point 801oC
− (2) boiling point 1413oC
3. Many other compounds due to
their structure have very weak
attractions between their
molecules
• a. sugar C12H22O11
• b. melts around 185-186oC
• 4. Comparing strengths of
attraction between molecules
• a. solids - strongest
• b. liquids - medium
• c. gases - weakest
Work
• 1. p 114
• 1-7
write questions and answers
II. 4.2 Ionic and
Covalent Bonding
• A. Ionic Bonds
• 1. defined - a bond formed
between oppositely charged ions.
• 2. There is an electron transfer
• a. one gains electron(s)
• b. one loses electron(s)
• 3. mostly between metals and
nonmetals
• 4. These form polar molecules
which will form a network of ions
• a. the positive side attracts the
negative side
− (1) how salt crystals are formed
• 5. Formula unit is the smallest
ratio of ions in ionic compounds
• a. Na+1Cl-1 or
Ca+2F2-1
• b. When melted or dissolved in H2O
ionic compounds will conduct
electricity because the ions are free
to move.
• c. As solids the ions are locked so
tightly that they do not conduct
electricity.
• B. Metallic Bonds
• 1. defined - a bond formed by the
attraction between positively
charged ions and the electrons
around them.
• 2. Metal to metal
• a. example: Cu
• 3. This allows the atoms to
• a. conduct electricity
− (1) electrons are free to move from one
atom to another atom
− (2) be more flexible to bend and stretch
without breaking.
– (a) atoms can slide past each other
without breaking their bonds
• C. Covalent Bonds
• 1. defined - a bond formed when
atoms share one or more pairs of
electrons.
• 2. often formed between nonmetal
atoms
• a. can be solids, liquids, or gases
• b. usually low melting points except
for compounds that form network
structures like SiO2
• 3. Do not conduct electricity
because the molecules remain
intact when melted or dissolved in
H2O.
• 4. Electrons are shared not
transferred with the nucleus of
each atom equally attracting the
electrons.
• a. This results in two types of
molecules
− (1) polar - NH3
− (2) nonpolar - CO2
• b. Atoms may share more than one
pair of electrons
− (1) O=O
− (2) N=N
• c. polar covalent bonds are formed
between two different atoms where
the shared electrons are attracted to
one nucleus more than the other
• D. Poly atomic Ion
• 1. defined - an ion made up of two
or more atoms that are covalently
bonded and that act like a single
ion.
• 2. most names end in -ite and -ate.
• a. -ide = the anion named only
− (1) CN-1 - cyanide
− (2) OH-1 - hydroxide
• b. -ite = the anion with one less
oxygen
− (1) SO3-2 - sulfite
• c. -ate = the anion with one more
oxygen
− (1) SO4-2 - sulfate
• 3. Use parentheses around them when
more than one is needed in the formula.
• a. (NH4)2SO4 - ammonium sulfate
• b. NH4NO3 - ammonium nitrate
• 4. Learn the poly atomic ions with there
name, symbol, and charge on page 122 as
follows:
acetate C2H3O2-1, carbonate CO3-2,
chlorate ClO3-1, hydroxide OH-1,
nitrate NO3-1, nitrite NO2-1,
cyanide CN-1, phosphate PO4-3,
sulfate SO4-2, sulfite SO3-2,
and ammonium NH4+1
•
•
•
•
Page 122
Questions 1-7
Write question and answers
Due at end of class
III. 4.3 Compound
Names and Formulas
• A. Compounds have names that
distinguish them from other
compounds and elements.
• 1. BaF2 - barium fluoride vs. BF3 boron trifluoride
• B. Ionic Compounds
• 1. Include the name of the ions of
which they are composed
• a. The cation (positive) is usually the
name of the element
− (1) K+ - potassium
− (2) Ba+2 - barium
• b. The transition elements we
use the element name plus a
roman numeral for the oxidation
number in that compound.
− (1) Fe+3 - iron III
− (2) Fe+2 - iron II
− (3) Ti+4 - titanium IV
• c. For the anion (negative) we use the
root of the element name and attach an
ending
− (1) -ide - only the root element makes up the
anion
− (2) iron II oxide FeO
− (3) fluoride - F-1; chloride - Cl-1; bromide – Br -1;
sulfide - S-2
− (4) remember the -ites and -ates have oxygen
with the root element
– (a) sulfate - SO4-2; phosphate - PO4-3
• 2. Writing formulas
• a. List the symbols for each ion.
− (1) example: for aluminum fluoride
Al F
• b. Write the symbols for the ions and their
oxidation number with the cation first.
− (1) Al+3 F-1
• c. Find the least common multiple of the ions
charges.
− (1) for 3 and 1 it is 3
− (2) you will need 3 positive charges and 3
negative charges
• d. Write the chemical formula, indicating with
subscripts how many of each ion is needed to
make a neutral compound.
− (1)
+3 -3 = 0
−
Al+3 F3-1
• 3. Practice p. 125 1-4
• 4. Some covalent compounds will
form more than one compound
with the same two elements
• a. We use a numeral prefix to indicate
the number of ions in that compound.
− Page 126
• b. example: CO - carbon monoxide and
CO2 carbon dioxide
• C. Empirical formula
• 1. defined - the simplest chemical
formula of a compound that tells
the smallest whole number ratio of
atoms in the compound.
• D. Molecular formula
• 1. defined - a chemical formula
that reports the actual numbers of
atoms in molecule of a compound.
• a. in some cases the molecular
formula is the same as the empirical
formula
− (1) formaldehyde - the empirical formula is
CH2O and a molecular formula of CH2O
− (2) acetic acid - the empirical formula is CH2O
and a molecular formula of C2H4O2
− (3) glucose - the empirical formula is CH2O and
a molecular formula of C6H12O6
• E. Gram molecular mass of a
compound
• 1. Ba(OH)2
• Element atoms molar mass/atom molar mass all
atoms
Ba
1
x 137.33 g/mole =
137.33 g/mole
O
2
x
16.0 g/mole =
32.0 g/mole
H
2
x
1.0 g/mole =
2.0 g/mole
171.33 g/mole
Ba(OH)2
• Ni3(PO4)4
• Element atoms molar mass/atom molar mass all atoms
Ni
3
x
58.69 g/mole =
176.07 g/mole
P
4
x
30.97 g/mole =
123.88 g/mole
O
16 x
16.0 g/mole =
256.0 g/mole
555.95 g/mol
Ni3(PO4)4
• 3. class work
• a. FeI2
• b. MnF3
• c. CrCl2
IV. Organic Chemistry
• A. Polymers
• 1. defined - a large organic
molecule made of many smaller
bonded units
• a. poly - many
• 2. properties are determined by its
structure
• a. some long thin chains
• b. some tangled like a bowl of
spaghetti
• 3. most of your plastic and rubber
products are polymers
• a. elastic - return to original shape
− (1) rubber bands
• b. non elastic - will not return to
original shape
− (1) plastic soft drink bottles
• Home work
• F. page 128
• 1-4; 6-7