Physical Properties and Changes of Matter, States of Matter

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Physical Properties and Changes of Matter, States
of Matter

• Physical properties of matter include color,
  shape, texture, smell, taste, phase of matter.
  Anything that you can tell by using your senses.

Physical changes do not change the substance
into another. Examples are tearing paper,
coloring water, ice melting.
Matter can be found in solid, liquid, gas, or
plasma state
An atom is made up of a tiny nucleus with
electrons around it
Chemical properties of matter include
combustibility and reactivity. These properties
can not be seen only witnessed when they occur.
Chemical changes can change one substance into
another new substance with different chemical
and physical properties.
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ELEMENTS,COMPOUNDS,MIXTURES

• All substances are made of atoms
• Elements are made of only one type of atom
• Compounds contain more than one type of atom
• Compounds are chemical bonded together
• Mixtures are physically combined together

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ATOMIC STRUCTURE

• Atoms contain PROTONS, NEUTRONS ELECTRONS
• Protons and Neutrons are found in the NUCLEUS
• Electrons orbit the nucleus

PARTICLE RELATIVE CHARGE RELATIVE MASS
Proton 1 (positive) 1
Neutron 0 (neutral) 1
Electron -1 (negative) 0
Any atom contains equal numbers of protons and
electrons

• ATOMIC NUMBER ? the number of protons in the
  nucleus
• ? the periodic
  table is arranged in this order
• MASS NUMBER ? the number of protons plus neutrons
• Number of neutrons Mass Number Atomic Number

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ELECTRON ARRANGEMENT

• Electrons are arranged around the nucleus in
  SHELLS (or energy levels)
• The shell closest to the nucleus has the lowest
  energy
• Electrons occupy the lowest available energy
  level

High energy shell
This is how we draw atoms and their electrons
Low energy shell
Sodium

• Atoms with the same number of electrons in the
  outer shell belong to the same GROUP in the
  periodic table
• Number of outer electrons determine the way an
  element reacts
• Atoms of the last group (noble gases) have stable
  arrangements and are unreactive

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METALS, NONMETALS, METALLOIDS
Valence electrons (outer shell) determine the
chemical properties of the elements Atoms want
to get 8 electrons in their Outers shells for
stability

• Each element has its own symbol in the periodic
  table
• Columns are called GROUPS.
• Elements in a group have similar properties
• Rows are called PERIODS
• The red staircase splits metals from non-metals

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FORMING BONDS

• Atoms can react to form compounds in a number of
  ways
• Transferring electrons ? IONIC BONDING
• Sharing electrons ? COVALENT BONDING

• IONIC BONDING
• When a metal and non-metal react
• Metals form positive ions
• Non-metals from negative ions
• Opposite charges attract
• A giant lattice is formed

• COVALENT BONDING
• When 2 non-metals bond
• Outermost electrons are shared
• A pair of shared electrons forms a bond

Evidence of Chemical Reaction
Formation of a solid (precipitate)
Temperature change
Color change
Gas production (bubbles)
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CHEMICAL EQUATIONS

• Chemical equations show the reactants (what we
  start with) and the products (what we end up
  with)
• We often use symbol equations to make life easier
• CaCO3 ? CaO CO2

• This is balanced same number of each type of
  atom on both sides of the equation
• We can check this by counting the number of each
  type on either side

Ca 1 C 1 O 3
Ca 1 C 1 O 3
H2 O2 ? H2O Add a 2 to the products
side to make the oxygen balance H2 O2 ?
2H2O This has changed the number of hydrogen
atoms so we must now adjust the reactant
side 2H2 O2 ? 2H2O
MAKING EQUATIONS BALANCEEquations MUST
balance We can ONLY add coefficients (BIG
numbers) to the front of a substance We can tell
elements within a compound by symbols (BIG
letters) CaCO3 ? this is a compound made of 3
elements (calcium, carbon and oxygen)
H 2 O 2
H 2 O 1
H 2 O 2
H 4 O 2
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Acids, Bases, and Salts
Radioactivity
Half life Time it takes for number of
radioactive nuclei/count rate to fall to half its
initial value Half lives
Time (s)
I break
U make
Acid Base --- Salt Water