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Chemistry Review Sheet 3

Be able to identify these people. ( there in order)

John Dalton was one of the pioneers in early atomic theory.

J.J. Thompson developed one of the first mathematical models of the atom.

Ernest Rutherford's experiments verified the structure of the "nuclear atom."

Neils Bohr developed an accurate mathematical model of the hydrogen atom.

Democritus philosopher who developed one of the first atomist theories of the universe.

The differences between these two men?

Mendeleev used atomic masses to classify the element, where as Moseley classified the element in terms of atomic number, he suggested that chemical and physical properties are the functions of the atomic number.

An atom is considered neutral when They have an equal number of protons (1) and electrons (-1) therefore the charge adds up to zero, which is neutral.

what is it called when you have the same element but with a different mass number? Isotope

What makes the mass # different ?Isotopes are atoms which have the same atomic number but different mass numbers. They have the same number of protons but different numbers of neutrons.

What do you get the atomic # by adding what ?

For any element:

Number of Protons = Atomic Number

Number of Electrons = Number of Protons = Atomic Number

Number of Neutrons = Mass Number - Atomic Number

The periodic law in chemistry, law stating that many of the physical and chemical properties of the elements tend to recur in a systematic manner with increasing atomic number.

Label the following groups - 1

Special about the noble gases re all very stable because they each have the maximum amount of electrons in their outer shell (8 for all except helium which has 2) .

NEED TO KNOW : AS THE ATOMIC # INCREASES WITHIN A GROUP OF ELEMENTS AND ATOMIC RADI USALLY DOES AS WELL.

How many electrons would be in Mg + 2 ion? An Mg2+ ion is a magnesium atom with a 2e positive charge. This means that it has two electrons (negative charge) less than protons (positive charge).

Magnesium as the atomic number 12. This means that each magnesium has 12 protons. Because Mg2+ has a net charge of +2e, it has 10 electrons, as explained above.

How many electrons would be in Cl - 1 ion? There are 18 in