Unit 3 Chemistry

exam time :(

Dmitri Mendeleev

• published first periodic table

• baed on increasing atomic mass

• left blanks for elements that weren’t discovered yet

Henry Moseley

used x-rays to confirm Mendeleev’s periodic chart

Periodic Law

states that the physical and chemical properties of the elements are periodic functions of their atomic numbers.

Group 1

Alkali metals

• strong bases

• explode when placed in water

Group 2

Alkaline earth metals

• elements found in nature

Groups 3-12

Transition Metals

• brightly colored

Groups 13-16

no name(losers)

• group 13 has 3 valence electrons, 14 has 4 valence electrons and so on.

Group 17

The Halogens

• all have 7 valence electrons

• most active nonmetals

• can form very strong acids

Group 18

Noble Gases

• perfect, non-reactie

• All have 8 valence electrons except for helium which only has 2.

Effective Nuclear Charge

the net positive charge experienced by an electron in an atom. (idk wtf this means but ok)

Ionization Energy

energy required to remove the valence electrons from an atom.

Electronegativity

the measure of the ability of an atom to attract shared electrons.

Heisenberg Uncertainty Principle

states you cannot determine the speed and location of a particular electron at the same time.

Photoelectric Effect

energy given off when light strikes a metal object.

Electron Oribtals

used to calculate the probability of finding an electron of an atom.

s-block

p-block

d-block

f-block

2 orbitals

3 orbitals

5 orbitals

7 orbitals

Aufbau’s Principle

protons are added one by one to the nucleus to build up the elements

1s → 2s → 2p → 3s → 3p → 4s → 3d → 4p → 5s → 4d → 5p → and so on.

Pauli Exclusion Principle

states no two electrons can have the same set of four quantum numbers(opposite direction).

Hund’s Rule

remain unpaired as long as possible

Principle Quantum Number

indicates the size of an atom

• symbolized by the letter “n”

Azimuthal Momentum Quantum Number

indicates the sublevels of the main energy levels

• symbolized by the letter “l”

Magnetic Quantum Number

indicates the orientation of electrons on an “x” “y'“ “z” axis.

• symbolized by the letter “m”

Spin Quantum Number

indicates the direction electrons are traveling by using alternating arrows

• symbolized by “m_2”

Ion

charged particles