Chem 7 - Periodic Properties of the Elements

Whos Mosley

Developed the concept of atomic numbers

Many electrons atoms do what?

electrons are both attracted by the nucleus and repelled by the other electrons

Effective Nuclear Charge (Zeff)

is the net charge experienced by an outer electron

What is Z

the atomic number

What is S

The screening constant

Effective nuclear charge equation

Zeff= Z - S

Z effect increase

When it goes from left to right

Z effect 

remains the same when it goes from top to bottom

Ionization ebergy decreases

from top to bottom

Electron affinity decreases

from top to bottom

Size (radius) increases

from top to bottom

Metallic character increases

from top to bottom

All metals…

tend to have a lower ionization energy

Nonmetals…

tend to have high electron affinities.

Nonmetal oxides react with water to form an …

Acid (Ex: CO2 (g) + H2CO3 (aq)

Nonmetal oxides react with bases to form…

salt and water (Ex: CO2(g) + 2NaOH(aq) — Na2CO3(aq) + H2O (l)

Alkali metals

react explosively with water, producing hydrogen gas and metal hydroxides. Reactivity increases going down the group.

Produces bright colors when places in a flame

Allotropes

are different forms of the same compound in the same phrase

Sulfer

is a weaker oxidizer than oxygen

Halogens

are all nonmetals

They have large, negative electron affinities.

Tend to oxidize other elements easily

They reacts directly with metals to form metal halide.

Iso-electronic ions

are ions with the same number of electronsI

Ionization energy

is the amount of energy required to remove an electron from the ground state of a gaseous atom or ion.

The first ionization energy

is the energy required to remove the first electron from a neutral atom

The second ionization energy

is the energy required to remove a second electron, from an ion.