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2.1 – Matter
all objects are made of matter
~ something with mass and
volume (remember the density
matter can usually be found on
Earth as a solid, liquid, or a gas
atom: building block of all matter
atoms are made up of smaller parts:
proton: particle that has a positive (+)
~ large in size
neutron: particle that has no charge
~ large in size (like a proton)
electron: particle that has a
negative (-) charge
~ very small
~ about 1/1800th the size of a
proton or neutron
atoms have no overall charge
(neutral) because there is an
equal number of protons (+) and
electrons (-)
nucleus: center of atom
~ contains protons and neutrons
electron cloud:
area of space that
surrounds the
~ contains the
electron cloud
Happy, happy Carbon atom!
But, are all parts really happy?
element: substance that can’t be broken
down into a simpler form
elements are organized by their
properties on the periodic table
95 naturally occurring elements with
only 8 making up most of Earth’s
element symbols are usually 1 or 2 letters
~ hydrogen = H, carbon = C, oxygen = O
each element has a different number of
~ hydrogen (H) = 1, carbon (C) = 6,
oxygen (O) = 8
number of protons is called the atomic
number of the element
in nature, there can be several versions
of the same element
same number of protons BUT have a
different number of neutrons
~ called isotopes
some isotopes are unstable and give
off neutrons which makes them
Hydrogen –
1 P, 0 N
Hydrogen 2 (Deuterium) –
1 P, 1 N
Hydrogen 3 (Tritium) –
1 P, 2 N
radioactive isotope
isotopes of the same element are
shown by writing the symbol and the
mass number
~ H-1, H-2, H-3
mass number: total number of protons and
neutrons in an atom
~ remember those are the two particles
with any measurable mass
~ electrons are too small!
Hydrogen –
1 P, 0 N
Hydrogen 2 (Deuterium) –
1 P, 1 N
Hydrogen 3 (Tritium) –
1 P, 2 N
The NEW Periodic Table
Read the lyrics to follow along!
compound: substance made from
atoms of 2 or more different
atoms are held together by a force
called a chemical bond
arrangement of electrons determines
how atoms bond together
electrons in the electron cloud are
grouped in different energy levels
each level can hold a limited
number of electrons
outer level can hold 8 electrons
(except for H and He)
~ is stable with outer level full
if the outer level ISN’T full, the atom
will bond with other atoms to get a
total of 8 in the outer shell
sometimes atoms will lose or gain
electrons in order to get a total of 8
electrons in their outer shell
atoms will then have a charge due to
an unequal number of electrons (-)
and protons (+)
~ those atoms are called ions
atoms that lose electrons are positive
ions (more P than e)
atoms that gain electrons are negative
ions (more e than P)
opposite charges attract so an ionic
bond forms between opposite ions,
creating crystalline ionic compounds
covalent bond: when atoms
share electrons to form a
covalent compound
since the number of protons (+) is
equal to the number of electrons
(-), the charge of the molecule is
neutral (no charge)
metallic bond: when atoms share
electrons between many metal
metal ions are positive so are
attracted to the negative electrons
because many ions are sharing many
electrons, metals have unique
easily shaped (malleable)
drawn into thin wires
conduct heat and electricity