Section 2: Matter Flashcards
Democritus (350 BC)
The first man to use the word ATOM.
Aristotle (350 BC)
Everything was made of earth, air, fire, and water.
Alchemists (350BC - 1500AD)
science with a bit of magic.
Gave us beakers, filters, plaster.
Boyle (1500 - 1750s)
Was convinced that matter was made up of tiny particles (like Democritus!)
Antoine Laurent Lavoisier & his wife Marie (late 1700s)
Developed chemical naming system.
Dalton (1800s)
Matter was made of elements.
(first one to call an element a pure substance)
JJ Thomson (late 1800s)
Discovered the electron. Made the Raisin Bun Model of Atoms.
Rutherford (1908)
Discovered the NUCLEUS in the gold foil experiment where positive charges were deflected.
Bohr (1908)
Electron Shell Model of the Atom..
Chadwick (1922)
Nucleus has protons and neutrons and is surrounded by electrons!
what is an atom?
3 parts to an atom?
smallest basic unit
protons (+)
electrons (-)
neutrons (neutral)
what order are elements listed on the periodic table?
increasing atomic mass (mass of one atom of an element)
atomic mass unit (amu)
Finding the number of PROTONS
.# of Protons = Atomic Number
finding number of electrons
.# of Electrons = same as Protons
(atomic number)
finding number of neutrons
.# of Neutrons = Atomic Mass - Atomic Number (protons)
Isotopes
different forms of the same element
can protons change?
no If the protons changed, it would be a different element all together.
can electrons change?
atoms can give or take electrons when they combine with other elements to form compounds.
can neutrons be different
mass listed on the periodic table is the MOST COMMON mass for that element.
metals
highly ductile and can be drawn into wire without breaking
non metals
are not very ductile and cannot be drawn into wire without breaking
metaloids
Some metalloids are ductile, while others are not
periods
horizontal rows
left to right, the elements gradually change from metals to non-metals
most reactive metals start on the left
groups/families
vertical columns
top:
- Metals: Reactivity low
- Non-Metal: Reactivity high
bottom:
- metals reactivity high
nonmetals reactivity low
Alkali Metals
most reactive
more reactive as you go down.
group 1
Alkaline Earth-Metals
their reactivity is not as strong as the alkali metals
group 2
Halogens
Most reactive non-metals.
can combine with other elements (form new useful substances)
group 17
noble gases
Most stable/unreactive elements.
group 18
Bohr Diagrams - 1st electron shell rule
2 electrons in the first shell
Bohr Diagrams - octet
Every other electron shell is full when it has 8 ELECTRONS (called an OCTET)
Bohr Diagrams - period/group rule
PERIOD: number of electron shells for an atom same as period number
GROUP: last number in the group shows the number of electrons in the outer (valence) shell!
