Transcript compound

Chapter 4: The Structure
of Matter
Section 1:
Compounds & Molecules

What are compounds?
 When
elements combine to form
a compound, the compound has
properties different from the
elements that make it.
◦ NaCl
Chemical Bonds
 Chemical
bonds distinguish compounds
from mixtures.
◦ Mixtures are made of _________substances
that are placed together.
 Each substance in the mixture keeps its own
properties.

Chemical Bonds are the attractive forces
that hold different atoms together in a
compound.

A compound always has the same chemical
formula.
◦ Ex. Water _________
◦ Table Sugar C12 H22 O11
◦ Glucose
__________

A Chemical Formula shows the types &
numbers of atoms in the compound

Compounds are always made of the
same elements in the same
proportions.
Chemical Structure shows the
bonding within a compound

The arrangement of atoms within a
compound determine many of its properties.
◦ Example: H2O

Bond Length: The avg. distance between
the nuclei of 2 bonded atoms

Bond Angles: The angle formed by 2 bonds
of the same atom.

Some structures are made of bonded ions.

Example: NaCl
◦ A repeating network connected by strong bonds
◦ Positive Na bonded to Negative Cl
 The
strong attractions between
oppositely charged ions give NaCl
high melting & boiling points
Some compounds are made of
molecules

Example: “Air”

Air contains Nitrogen, Oxygen, & Carbon
Dioxide.
◦ All 3 substances are made of molecules
 Atoms
within each molecule are
strongly bonded. The attraction
between the different molecules are
not as strong
Chapter 4 Section 2: Ionic &
Covalent Bonds
1.
The outermost energy levels of a
bonded atom is full of
____________.
2.
Atoms bond when their
__________ electrons interact.
3.
Generally, atoms join to form bonds
so each atom will have a full outer
energy level.
Ionic Bonds
4.
Form between oppositely charged ions
4. Na+ Cl-
5.
Metals form _______________ charged
ions.
6.
Nonmetals form____________ charged
ions.
7.
Ionic Bonds are formed by the
________of electrons.
Properties of Ionic Compounds
1.
2.
3.
4.
Will form between metals & nonmetals
When melted or dissolved in water,
ionic compounds conduct
___________.
Electric current is moving charges
Solid ionic compounds do not conduct
electricity because their particles have
very little movement.
Metallic Bonds
1.
Electrons move freely between metal
atoms
2.
A Metallic Bond is a bond formed by
the attraction between positively
charged metal ions & the elements
around them
3.
In metallic bonds the outer levels
overlap and electrons move freely from
atom to atom.
Covalent Bonds
1.
Electrons are _________ between bonded
atoms.
2.
Often formed between nonmetals
3.
Most covalent bonds have a ______ melting
point
1. Due to weaker bonds between atoms.
4.
Atoms are free to move in compound & do not
conduct electricity (not charged)
Polar Covalent Bonds

When 2 different atoms share electrons, they
are not shared ___________.

A Polar Covalent Bond is formed by the
unequal sharing of electrons

Electrons are more attracted to the elements
located on the far right (____________)
Polyatomic Ions

Compounds that have both ________ &
___________ bonds are polyatomic

Example: Baking Soda & Ammonium nitrate

Parentheses group the atoms of a
polyatomic ion. (NH4)2SO4
◦ Indicate when elements act as a single ion.

The charge applies to the whole ion
Chapter 4 Section 3
Compound names & formulas
 Compound
names & formulas are
related
 Compound
names reflect the elements
which they are made of.
Group Charges

Group 1 = 1+

Group 2 = 2+

Groups 3-12 (Tend to have more than one charge)
◦ Can lose valence electrons as well as lower level electrons

Group 13 = 3+

Group 14 = 2+ or 4+
Group Charges

Group 15 = 3-

Group 16 = 2-

Group 17 = 1-

Group 18 = 0 (stable/noble gases)
Lanthanides = 3+
 Actinides = 3+ or 4+

Naming Ionic Compounds
 Ionic
Compounds are formed between
anions & cations. (nonmetals & metals)
 When
atoms lose electrons they are
written with a_________ charge
◦ Ex. Sodium loses one e- (Na+)
 Calcium loses two e- (Ca 2+)

Table 4-4 shows common names & symbols
for cations.
 An
anion (________) that is made of
one element has a name similar to the
element
◦ Example: Flourine becomes a flouride ion
when combined with a cation.
◦ Table 4-5 (common anions)
 Most
anions have the same charge as
elements in their same _________.
Ex. Calcium Chloride
Calcium has a charge of ______
 Chlorine has a charge of ______


How can you balance the compound?

CaCl2
How can you determine the charge of a
transition metal?

Like all compounds, ionic compounds
have a total charge of ________.

This means the total positive charge of
the cation must equal the total negative
charge of the _________.

Example: An Oxide ion, O2- has a charge of
_____. 3 ions would have a total charge of
______.
Some cation names must show their charge

Example: FeO & Fe2O3

Iron is a transition metal which can form
many cations each with a different
charge. (table 4-6)

The cation must be followed by a Roman
Numeral in parentheses
◦ Example Fe2O3 iron(III)oxide
Writing Formulas For Ionic
Compounds

You can determine the formula for a
chemical compound by looking at its
name

Example: Aluminum Flouride
Practice Problems
1.
Lithium Oxide
2.
Beryllium Chloride
3. Titanium (III) nitride
4. Cobalt (III) Hydroxide
Practice Problems
1. Magnesium Bromide
2. Rubidium Oxide
3. Lithium Nitride
4. Potassium Sulfate
Ions will end in what suffix?

What is the charge of
a cation?



What is the charge
of group one?
What is the charge of
an anion?

What is the charge
of group 18?
Balanced Chemical
compounds have an
overall charge of
what?

What is the charge
of group 2?
Naming Covalent Compounds

Covalent compounds are named using
different rules.

Numerical Prefixes are used to name
covalent compounds of 2 elements
◦ Tell how many atoms of each element are in
the compound (Table 4-7)

Example: Triflouride
 Dinitrogen tetroxide
Numerical Prefixes (pg. 126)
1
2
3
4
5
6
7
8
9
10
MonoDiTriTetraPentaHexaHeptaOctaNonaDeca-
Practice 
 MnF3
 FeO
 Titanium(III)
Sulfide
Practice 

1. Diarsenic Pentoxide

2. Carbon Dioxide

3. Tetraphosphorus Trisulfide

4. Phosphorus Hexoxide
Empirical Formula

A compound’s simplest formula is its
empirical formula.
◦ Tells the smallest whole-number ratio of
atoms in the compound

Example: H20 2:1

Scientists have to analyze unknown
compounds to determine their empirical
formula.
An unknown compound weighs
142 g.
It contains the O & P.
It has 62 g of P & 80 g of O.
How can you calculate its
empirical formula?
Convert the mass in to moles!

What is the conversion unit for
converting mass into moles?
How many moles of P have a mass of 62g?
How many moles of O have a mass of 80g?
Different compounds can have the
same empirical formula.

Example: Formaldehyde, Glucose, & Acetic
Acid (Vinegar) all have the same empirical
formula = CH2O

What formula can be used to determine
the difference between similar
compounds?

Its Molecular Formula!!
 Molecular
Formulas are determined from
empirical formulas
 Molecular
formulas show the actual
numbers of atoms in one molecule of a
compound.
 Covalent
Compounds have both
empirical & molecular formulas.
Chapter 4 Section 4
Organic & Biochemical Compounds

An Organic Compound is a covalently
bonded compound made of molecules

In a covalent bond electrons are
_________.

In an ionic bond electrons are
__________.
Organic Compounds contain
__________.
 Almost
 May
always contain hydrogen
contain oxygen, nitrogen, sulfur, &
phosphorus
 Carbon
atoms form 4 covalent bonds in
organic compounds
 When
a compound is made only of
carbon & hydrogen it is a hydrocarbon
◦ Example: methane (C-H)
 Carbon
can also form double bonds
or triple bonds with other atoms
Alkanes have single covalent bonds &
names end with -ane

Alkanes are hydrocarbons that have only
single covalent bonds
◦ Example: Methane C-H (simplest alkane)

Alkanes can also have bonds between
carbons (C-C)
◦ Example: Ethane C2H6
◦ Each Carbon atom bond with 4 other atoms
Arrangement of carbon atoms
 When
3 or more carbon atoms are
bonded they do not always line up in a
row. (structurally)
 When
the atoms DO line up they are
named “normal alkanes” ( nalkane)
 Alkanes
with more than 3 carbon
atoms have many possible
arrangements.
 They
can be Branched,
Unbranched, or form Rings (Figure
4-26)
Alkane formulas

Except for cyclic alkanes, the chemical
formula always has a special pattern

The # for Hydrogen atoms is 2 more than
twice the number of carbon atoms.

Example: C3 H8
Alkenes have Double carbon- carbon
bonds (-ene)

Alkenes are hydrocarbons

Different from alkanes because they have
at least one double covalent bond
between carbon atoms

C=C
Alkenes
Examples:
Ethylene C2H4
Propylene C3H6
Alcohols have –OH groups
end in “ -ol ”

Alcohols organic compounds are made of
Oxygen as well as hydrogen & carbon

Alcohols have hydroxyl, or –OH groups

Example: Ethanol
◦ CH3CH2OH
 Alcohol
molecules behave similarly to
water molecules
 Neighboring
molecules are attracted to
one another
◦ Properties of adhesion & cohesion

Alcohols are liquid at room temperature but
have very high boiling points
Polymers

Large molecules made of smaller subunits

Many polymers have repeating subunits
◦ Example: polyethene

Polymers exist naturally & can be synthetic

Natural: rubber, wood, cotton, wool, starch,
protein, DNA

Synthetic: Plastics or Fibers
A
Polymer’s elasticity is determined by
its structure
 (Similar
to a chain) When the
monomers are liked together the
polymer becomes elastic.
Biochemical Compounds
 Naturally
occurring organic
compounds that are very
important to living things.
 Example: Carbohydrates, Proteins,
& DNA
1. H7Cl2
_________________________________
 2. C4Br6
__________________________________
 3. P3O10
_________________________________

5.N5F8
 ________________________________


Naming Ionic Practice:

__________________________ CaCl2

________________________ K2O

___________________________ MgO
Chapter 4 Vocabulary Quiz
1. A compound made
only of hydrogen and
carbon
2. The simplest chemical
formula of a compound that
tells the smallest whole
number ratio of atoms in
the compound
3. Any one of 20 different
naturally occurring
organic molecules that
combine to form
proteins
4. Any organic compound
that is made of carbon,
hydrogen, & oxygen and
that provides nutrients to
the cells of living things
5. Any covalently bonded
compound that contains
carbon
6. A biological polymer
made of bonded amino
acids
7. A large organic
molecule made of many
smaller bonded units
8. Hydrocarbons that
have only single covalent
bonds
9. A Chemical Formula that
reports the actual numbers of
atoms in one molecule of a
compound
10. A bond formed by the
attraction between
oppositely charged ions