Early Discoveries and the Atom (2.1.1) Flashcards
• The Greek philosopher Democritus described matter as being composed of indivisible particles called “atoms”.
• The Greek philosopher Democritus described matter as being composed of indivisible particles called “atoms”.
• Dalton published his atomic theory of matter in 1808.
• Dalton published his atomic theory of matter in 1808.
• Atoms consist of protons, neutrons, and electrons.
• Atoms consist of protons, neutrons, and electrons.
The Greek philosopher Democritus (460-370 B.C.)
described matter as being composed of indivisible
particles called “atoms”.
The Greek philosopher Democritus (460-370 B.C.)
described matter as being composed of indivisible
particles called “atoms”.
Dalton published his atomic theory of matter in
1808.
Dalton’s atomic theory of matter had four parts:
1) All matter is composed of indivisible atoms. 2) An
element (such as carbon or oxygen) is a type of
matter composed of one type of atom with a
characteristic mass. 3) A compound (such as
carbon dioxide) is a type of matter composed of two
or more elements in fixed ratios. 4) A chemical
reaction consists of the rearrangement of the atoms
in the reactants (such as the rearrangement of the
carbon atoms in graphite and the oxygen atoms in
oxygen to form molecules of carbon dioxide).
It was later shown that atoms are actually divisible
into subatomic particles, and elements can have
more than one mass (depending on the number of
neutrons in an atom of that element).
Dalton published his atomic theory of matter in
1808.
Dalton’s atomic theory of matter had four parts:
1) All matter is composed of indivisible atoms. 2) An
element (such as carbon or oxygen) is a type of
matter composed of one type of atom with a
characteristic mass. 3) A compound (such as
carbon dioxide) is a type of matter composed of two
or more elements in fixed ratios. 4) A chemical
reaction consists of the rearrangement of the atoms
in the reactants (such as the rearrangement of the
carbon atoms in graphite and the oxygen atoms in
oxygen to form molecules of carbon dioxide).
It was later shown that atoms are actually divisible
into subatomic particles, and elements can have
more than one mass (depending on the number of
neutrons in an atom of that element).
Atoms consist of electrons, protons, and neutrons.
Electrons are over 1800 times lighter than protons,
and have a negative charge.
Protons have a positive charge. Each element has
a characteristic number of protons.
Neutrons are slightly heavier than protons, and have
no charge.
J.J. Thompson determined the charge-to-mass ratio
for the electron from the behavior of a stream of
electrons in a cathode ray tube exposed to electric
and magnetic fields.
Atoms consist of electrons, protons, and neutrons.
Electrons are over 1800 times lighter than protons,
and have a negative charge.
Protons have a positive charge. Each element has
a characteristic number of protons.
Neutrons are slightly heavier than protons, and have
no charge.
J.J. Thompson determined the charge-to-mass ratio
for the electron from the behavior of a stream of
electrons in a cathode ray tube exposed to electric
and magnetic fields.
What are Atoms?
Small building blocks with mostly consistent weights and properties. One type of element will always have a certain amount of protons.
What are Compounds?
Grouped together atoms that form bonds and contain new properties.
Oscilloscope -
an electronic device which scans an electron beam across a phosphorescent screen
