Transcript Chapter 5 Notes: The Structure of Matter

Integrated Science I
 When elements combine, new properties are formed!
 Ex) Sodium is a shiny, soft, slivery metal that reacts
violently with water
 Ex) Chlorine is a poisonous greenish-yellow gas
 Together, they combine to make ordinary table
salt
 Shows what elements are in a compound
 Shows the exact number of atoms of each element
 Subscripts (written below) = how many atoms of the
element
0 has two hydrogen atoms for every 1 oxygen
 Ex) H2
atom
 Elements form compounds when the compound is more
stable than the individual atom(s)
 Ex) Nobel Gases remain individual elements because they are
already stable with full outer electron levels
 Ex) Other elements combine to fill their outer energy levels
 Atoms are chemically stable when their outer energy level
is filled
 Atoms gain, lose, or share for a total of eight electrons in
the outer energy level, this is called the octet rule.
 Two types of compounds:
 Ionic
 Covalent
 Ionic compounds are
formed from the attraction of
positive and negative ions.
 Positive ions are metals on
the left side of periodic table
 Negative ions are gasses on
the right side of periodic
table
 Electrons are taken from
another element to fill outer
energy level (8 electrons
needed)
Ex) What does it look like when magnesium and
chlorine bond?
Mg +2
 Step 1: Identify metal (with charge): ______________________
Cl
-1
 Step 2: Identify nonmetal (with charge): __________________
 Use the crisscross method to balance charges.
2+
1-
Mg Cl
 Step 3: Write symbols & charges: ______________________
MgCl2
 Step 4: Crisscross and change to subscript: ______________
****always remember to reduce
Ex) What does it look like when calcium and oxygen
bond?
Ca +2
 Step 1: Identify metal (with charge): ______________________
O
-2
 Step 2: Identify nonmetal (with charge): __________________
 Use the crisscross method to balance charges.
2+ O2Ca
 Step 3: Write symbols & charges: ______________________
CaO
 Step 4: Crisscross and change to subscript: ______________
****always remember to reduce





Formed between a metal and nonmetal
Step 1: Write the full name of positive ion
Step 2: Write the root name of negative ion
Step 3: Add ending –ide to the end of negative ion
Subscripts are not part of the name!
Ex) Use your periodic table to write the name for the following
binary ionic bonds:
1. NaCl
Sodium Chloride
____________________________________
2. BeO
Beryllium Oxide
____________________________________
 REMEMBER: Pure elements have equal numbers of
protons and electrons
 Ex) Sodium has 11 protons (+) and 11 electrons (-)
 This makes its charge zero because the + and – balance
 In an ionic bond, an element loses or gains electrons
from its outer energy level, which makes their charge
unbalanced
 Ex) Sodium has 1 electron its outer energy level, which is
lost when it bonds with chlorine.
 Now Sodium has 11 protons (+) and 10 electrons (-)

This makes its charge 1+ because there are more + charges
 Ionic numbers follow trends/patterns like group
numbers
 Metals lose electrons and become positive ions
 Gasses gain electrons and become negative ions
 Crystal lattice structure: alternating positive and
negative ions in ionic compounds make a crystal
lattice structure.
These compounds are brittle solids. The smallest ratio
of positive and negative ions make up the formula of the
compound
 Covalent bond is formed when atoms share electrons
 Formed between 2 nonmetals
 A molecule is formed from the sharing of electrons
in a covalent bond
 Some can form more than one compound with each
other
 Example: nitrogen and oxygen can form
 N2O
 NO
 NO2
 N2O5
 Use Greek prefixes for
the first and second
element
 Do NOT use prefix for
first element if it is
mono
 Ex) CO2
 Carbon dioxide
 Ex) N2O4
 Dinitrogen Tetraoxide
Total
Atoms
1
2
Prefix
monodi-
3
4
5
tritetrapenta-
6
7
8
hexaheptaocta-
 N2O =
Dinitrogen Monoxide
__________________________
 NO =
Nitrogen Monoxide
__________________________
 NO2 =
__________________________
Nitrogen Dioxide
Dinitrogen Pentoxide
 N2O5 = __________________________
Ionic
Covalent
Electrons
Gain/Lose to become neutral
Share to become neutral
State of Matter
Solid
Mostly Liquid
Freezing Point
High
Low
Boiling Point
High
Low
Texture
Sometimes brittle
Often rubbery
Solubility
Most will dissolve in liquids
Very few dissolve
Conductivity
High
Low
Composition
Made from metal and
nonmetal
Made from two nonmetals
(gasses)
 The Law of Conservation of mass and energy states
that matter can never disappear! It simply changes
forms
 If elements bond together, they do not disappear, they
simply combine together to form a new substance!
Balancing Chemical Equations
 Chemical Equations – A representative of a chemical
reaction that uses symbols and formulas to show
reactants and products
 Reactants = left side
 Products = right side
 Law of Conservation of Mass means amounts of
products and reactants must be equal!
Parts of a Chemical Equation
 Use coefficients to represent the number of units of
each substance in a reaction (kind of like the
number of ingredients in a recipe)
 Use subscripts to represent the number of atoms in a
molecule of a particular element
How to Balance Chemical
Equations
 Choosing coefficients becomes easier with practice
 At first it is trial and error
 A four-step process:
 1. Describe the reaction in words in your head
 2. Write the equation using formulas and symbols if it is
not already written that way
 3. Check for balance with numbers under
 4. Add coefficients where needed for balance
Chemical Equation Practice #1
 P + O2  P4O10
(Step 1: Find total atoms of P and O on each side)
4
___
1 P ___
___
2 O ___
10
 Now use coefficients to balance
5 2  ___P
4 + ___O
1 4O10
 ___P
4 P ___
4
___
10 O ___
___
10
Chemical Equation practice #2
 Al2O3  Al + O2
 Answer:
 2Al2O3  4Al + 3O2
Chemical Equation Practice #3
 BaCl2 + H2SO4  BaSO4 + HCl
 Answer:
 BaCl2 + H2SO4  BaSO4 + 2HCl
How Can a Chemical Reaction
Speed Up?
 Factors that cause chemical reactions to happen
faster:
 High temperatures (think about mold)
 Large surface area because there are more particles that
can react
 Concentration level
 High pressure
 Catalysts