Unit 9- Periodic Table

said that all matter was continuous

Proposed the idea of the atom

All elements are made of atoms

1. All elements are made of atoms 2)All atoms of the same element are identical (wrong) 3)Atoms of different elements combine with other atoms in whole number ratios 4)Reactions occur when atoms are separated, joined, or rearranged (later on nuclear chemistry was also discovered

1. Discovered the electron (using a cathode ray tube)

2. Discovered that electrons are negatively charged and they have mass

3. Made the "Plum Pudding Model"

Who performed the Gold foil experiment?

1. Discovered the proton and the nucleus Conclusions

2. Atoms have a small positive center that contains positively charged protons

3. The nucleus makes up almost all of the atom's mass

4. Atoms are mostly empty space

Discovered the neutral neutron in the nucleus (has no charge, but has mass)

He made the planetary model of the atom

A modern model of an atom

Using probability models, scientists can predict a cloud of where electrons are 90% of the time.

Positive charge (+1) Mass= 1 amu

0 charge Mass= 1 amu

Negative charge (-1) Mass= 1/1837 amu

amu stands for

Who used circular symbols to represent the elements?

Suggested the use of letters to symbolize elements

Organized the first periodic table

The number of protons (which is equal to the number of electrons)

The sum of the number of protons and neutrons (round the atomic mass, which is only an average)

M.A.N M-A=N M= Mass A= Atomic # N= Neutrons

An atom with the same number of protons, but a different # of neutrons (the exception to "all atoms of an element are identical")

Noticed there was a pattern in chemical properties every 8 elements with increasing atomic mass

Perfected the arrangement of the elements by placing them in order of atomic number instead of atomic mass.

Have similar chemical properties Have the same # of electrons in their outer shell

Horizontal rows of elements in the periodic table

All elements to the left of the zig- zag line on the PT Have some common properties

1. Solids at room temp. except for mercury

2. Shiny (Luster)

3. Good conductors (heat and electricity)

4. Ductile- can be rolled into wire

5. Malleable- can be pounded into sheets

All elements to the right of the zig- zag line on the periodic table. Have common properties (gases at room temp., do not conduct heat or electricity)

Next to the zig- zag line Have properties of both metals and non- metals

Group 1 Li, Na, K, Rb, Cs, Fr Shiny, highly reactive in water Lose an electron to form a +1 charge

Group 2 Be, Mg, Ca, Sr, Ba, Ra Shiny, highly reactive in water Lose 2 electrons to form a +2 charge

Groups 3-12 on the Periodic Table Less active than metals in groups 1 and 2

Dull (not shiny) Brittle and powdery (not malleable nor ductile) Poor conductors

Makes up 90% of all the atoms in the universe Diatomic molecule (has 2 atoms of the same element)- H2 Highly reactive because it has 1 electron

Group 17/7 Means "salt former" Have 7 electrons and want to gain one more to form a -1 charge *group 1 and 17 will often combine to form a neutral molecule

Group 18/8 Very stable and unreactive Have a full outer energy level (8 electrons)

Group 13/3

Group 14/4

Group 15/5

Group 16/6