Transcript Chapter 4 Study Sheet

Chapter 4 Study Sheet
Atomic Theory
for 6th Graders
Matter is anything that has
mass and takes up space.
Who’s that guy??

Lavoisier is the scientist who introduced
the law of conservation of matter. It
says that matter is neither created nor
destroyed, but only changes form.
John Dalton is a scientist who developed
a model called the atomic theory of
matter. It said that atoms are too small
to be seen by the human eye and that
each type of matter is made of only one
kind of atom.
J.J. Thomson is a scientist who conducted
experiments with a cathode ray tube,
and discovered invisible negatively
charged particles called electrons.
Ernest Rutherford is a scientist who did
experiments with gold foil and discovered
that atoms had a central part called a nucleus
and that in there are positively charged
particles caled protons, He also discovered
that an atom is made up mostly of empty
space.
A scientist named James Chadwick
discovered that the extra mass in atoms
were due to neutrally charged particles
in the nucleus called neutrons.
In the modern atomic model, we know
that electrons do not orbit around the
nucleus like Jimmy Neutron’s logo.
Instead, they move in what is called the
atom’s electron cloud.
Elements are made up of only one kind of
atom.
There are 115 known elements.
90 of them occur
naturally.
The Periodic Table is sorted by atomic
number, which tells how many protons
are in the nucleus of the element’s
atoms.
Some elements
have atoms with
different number
of neutrons in
their nucleus.
These are called
isotopes.
When you add the number of protons and
neutrons together, you get the mass
number.
The number found below the element
symbol on the periodic table, which is
the weighted average mass of all the
isotopes of the element, is the atomic
mass.
Metals have a shiny or metallic luster and
are good conductors of heat and
electricity. Most metals are solids at
room temperature. Metals are
malleable, which means they can be
shaped. Metals are also ductile, which
means they can be drawn into wires
without breaking.
carbon
Sulfur
Non metals are usually dull in
appearance. Most are poor conductors
of heat and electricity. Many are gases
at room temperature. Solid nonmetals
are generally brittle, meaning that
cannot change shape easily without
breaking. 97% of the human body is
made of of non metals.
Metalloids have characteristics of both
metals and nonmetals. They do not
conduct heat and electricity as well as
metals. All metalloids are solids at
room temperature.
A substance is matter that has the same
composition and properties throughout.
A compound is a substance whose
smallest unit is made up of atoms of
more than one element.
A chemical formula tells which elements
make up a compound as well as how
many atoms of each element are
present.
H20 = 2 atoms of hydrogen and 1 atom of
water
A subscript number (the tiny number
written below and to the right of each
element’s symbol) tells how many
atoms of that element are in the
compound.
C6H12O6= 6 carbon
6 hydrogen
6 oxygen
No subscript number is used when only
one atom of the element is present.
CO2 =
1 carbon
2 oxygen
A given compound is always made of the same
elements in the same proportion (ratio).
For example…in water (H20)
You will always have twice as many hydrogen
molecules as oxygen, whether you have a
drop or an ocean full.
A mixture is two or more substances
mixed together which don’t make a new
substance.
Unlike compounds, the proportions of the
substances in a mixture can be changed
without changing the identity of the
mixture.
What if you had more
crunchberries in your
Captain Crunch? Would
it still be Captain
Crunch?
In a mixture, you can separate the
different substance from each other.
There are two different kinds of mixtures.
In a homogeneous mixture, they are the
same throughout.
In a heterogeneous mixture, you can see
the different parts.