Transcript The Nature of Matter

The Nature of Matter
From Atoms to Bonds
Atoms
• Atoms=Basic unit of
matter
• Made up of three
subatomic particles
• Nucleus
– Densest region of atom
– Proton +
• In Nucleus
– Neutron
• In Nucleus
• Moving around nucleus
– Electron • Surrounds Nucleus
– In constant motion
Proton
• Has a positive charge
• # of protons=Atomic
Number
– Ex: gold (Au) has an
atomic # of 47 which
means it has 47
protons.
Neutron
• Has a neutral charge
• # of neutrons = Atomic Mass Atomic Number (#of protons)
• Ex: gold (Au) has an atomic #of 79
and an atomic mass of 197. How
many neutrons are in gold?
– 197-79=118 neutrons
Electron
• Has a negative charge
• # of protons= #of
electrons
• Balances out protons
positive charge
• In constant motion
• Valence electrons are in
outermost shell
• Valence electrons
determine the chemical
nature of an atom
• Smallest subatomic
particle
Elements
• Made up of ONE type
of atom
• Ex: carbon, hydrogen,
oxygen, nitrogen and
gold.
• Basically, any element
on the periodic table.
Molecules
• General definition: molecules are the
smallest part of a compound.
• Formed by combining 2 or more of the
SAME atom or DIFFERENT atoms
• Note: molecules are covalently bonded
• Ex: H2, O2, N2 ,H20, C6H12O6
Compounds
Water H20
• Made of molecules
formed by different
atoms.
• Formed by
COMBINING 2 Table Salt NaCl
or more different
elements in the same
proportion.
• Atom is to element AS molecule is to
compound
– Atom is the smallest unit of an element
– Molecule is the smallest unit of a compound
Chemical Bonds
• Ionic Bonds
• Covalent Bonds
Ionic Bonds
• Formed when electrons
TRANSFER from one
atom to another.
• When one atom loses an
electron it gains a positive
charge.
– This atom is now called a
cation.
• When one atom gains an
electron it becomes
negative.
– This atom is now called an
anion.
Covalent Bonds
• Formed when
electrons are
SHARED between
atoms.
• When atoms join
together by covalent
(sharing) bonds, it is
called a molecule.
• Compounds are made
up of molecules.