Chemistry Adv. 2.1-2.3

Dobereiner

Traids (groups of 3 based on properties); middle element had properties of the 2 around them.

Newland

Octaves (groups of 8); understood that properties repeated (where the word periodic in periodic table comes from)

Mendeleev

• Called the “Father of the Modern Periodic Chart”

• Published a periodic chart that arranged

  elements according to atomic mass AND

  properties

  • Several were “out of order” (e.x., Te and I)

• Left areas of table blanks for undiscovered elements

  • was able to predict their properties

Henry-Mosely

realized elements are in order of atomic # instead of atomic mass.

Properties

Elements in the same group tend to have the same…

Stair-step lines

divides metals and non-metals; contains metaliods

Most left of the periodic table (Alkali Metals)

Most reactive metals are where in the periodic table.

Most right of the periodic table (not including Noble gases, so Halogens)

Most reactive non-metals are where in the periodic table.

Metals

• Mostly solids

• Heat and electric conductors

• Shiny

• Malleable

• Ductile (pulled into a thin wire)

• Form alloys with improved properties (steel)

Metalloids

• All are solid

• Less conductive than metals

• Can be shiny or dull

• Tend to be brittle

• Used in alloys

• Semi-conductors (silicon)

Non-metals

• Solids, liquids, or gases

• Poor heat and electric conductors (except graphite)

• Dull

• Brittle (shatter easily)

Mercury (Hg) and Bromine (Br)

Only liquids at room temperature

Family

1+ groups of elements w/ similar properties.

Main Group Elements

s and p blocks; properties follow predictable pattern across a period and within a group

Noble Gasses

The Non-reactive group in the periodic table

Reactivity

how strongly/quickly elements react

metallic character

fewer valance electrons, (least amount is more reactive)

Non-Metallic Character

more valance electrons; (less than 8 valence electrons →more reactive)

Core Electrons

electrons that aren’t valence; closer to the nucleus → greater force of attraction.

Columb’s Law

• The strength of force between 2 charged particles depends on the charge of the particles and the distance between them.

• Opposite charges attract.

Increase in force of attraction

Increase in charge →

Increase of distance

Decrease of attraction →

the core electrons

Valance electrons are repelled by

the nucleus

Valance electrons are attracted by

Groups

• Vertical Columns

• 18 in total

• Elements in the same group tend to have the same properties b/c they have the same number of valance electrons.

Periods

• Horizontal rows

• 7 total

• Valance electrons of elements are located on the same energy level.

Alkai metals

• Group 1 (not including hydrogen)

• Soft, silvery-white, lustrous

• Highly reactive (increasingly reactive as you go down the group)

• Must be stored in oil because they are high reactive with water

Alkaline earth metals

• Group 2

• Similar to alkali metals

• not as reactive as alkali metals, so some don’t have to be stored in oil

• Harder and more brittle than alkali metals

Transition Metals

• Groups 3-12

• Basic metal properties

• Less reactive than alkali metals and alkaline earth metals

• Many compounds are colorful

Halogens

• Group 17

• General properties of nonmetals

• Solids, liquids, and gases

• Highly reactive (reactivity increases going UP the group)

Noble gases

• Group 18

• inert (non-reactive) groups

Lanthanide

• Top part of the 2 separate rows

• 15 elements starting with lanthanum

• Included in the ‘“rare earth” category

Actinides

• Lower part of the 2 separate rows

• 15 elements, starting with actinium

Atomic Radius

• Size of the atom

• ½ the distance between the nucleus of one atom and the nucleus of an adjacent, identical atom.

• Gets bigger on the Lower Left side of the periodic table

  • this is b/c the more protons, the more pull → smaller radius; more energy levels, more distance from the nucleus → larger radius

Ionization Energy

• Amount of energy required to remove an valance electron

• Decreases down a group (valance electrons are farther away from the nucleus, shielded from the attractive forces of the nucleus →less energy to remove an electron)

• Increases left to right along a period (valence electrons are held more tightly as the atom size shrinks →more energy to remove an electron)

Electronegativity

• The ability of atoms to attract electron from other elements for bonding

• Increases left to right (b/c the atoms become smaller on the right, so it’s easier to pull in extra electrons)

• Decreases down a group (b/c the more energy levels, the less attraction)

Common Oxidation numbers/Common Charge

• the total number of electrons that an atom either gains or loses in order to form a chemical bond with another atom.

• +1, +2, +3, +4, -3, -2, -1, 0

  • Groups going left to right not including the transition metals.

Electron Affinity

• The energy change that happens when an atom gains an electron.

• Increases left to right in a period (more electrons, the bigger the effect)

• Decreases down a group (the more energy levels, the lower it goes)