Chemistry

Periods

All the elements in a period have the same number of electron shells (also called orbitals or principal energy levels). For example, all elements in period 3 have 3 shells of electrons.

Nonmetals

Are dull, brittle, and are poor conductors of heat ad electricity.

Metals

Are lustrous, malleable, and are good conductors of heat and electricity.

Reactive metals and nonmetals

Are not found in nature ni their combined state (as pure elements). They always chemically bond with another element to form a compound.

Hydrogen

Non-metal

Metalloids (1) Metalloids (2)

(1)Boron, Silicon, germanium, arsenic, antimony and tellurium) (B, Si, Ge, As, Sb, and Te) have properties of both metals and nonmetals. (2) Metalloids are located on the "staircase" with the exception of aluminum, polonium, and astatine ( Al, Po, and At).

Going down a group

-An electron shell is added -Atomic radius increases -There is more distance between the positive nucleus and the valence electrons. -The nucleus cannot attract electrons -(Low electronegativity) -The nucleus holds its valence electrons Loosely (low ionization energy) -Going across period; the charge on the nucleus increases. In period 2 for example, the electrons are added to the second principal energy level are pulled closer to the nucleus and atomic radius decreases.

Transition metals

-Have multiple positive oxidation states -Elements in a group may have different number of valence electrons -Have colored ions -The outermost electron shell is the valence shell. The electrons in the valence shell are called valence electrons. Carbon has 4 valence electrons Groups are columns going down Periods are rows going across

Ionization energy

-Is the amount of energy needed to remove an electron from an atom. -Fluorine (F) has the highest ionization energy (1681kJ/mol) (with the exception of the noble gases). It is very difficult to remove an electron from a fluorine atom. -Francium and cesium (Cs) - have the lowest ionization energies. It is very easy to remove an electron from a Francium atom.

Going across a period

-The increasing charge in the nucleus pulls the electrons in closer to the nucleus and atomic radius decreases. -The number of shells between the positive nucleus and the valence electrons remains the same. -The increasing charge in the nucleus can attract electrons from other atoms (high electronegativity) -The nucleus holds its valence electrons tightly (High ionization energy)

Atomic Radius

-The measure of the size of an element's atom (Table S) -Francium is the most reactive metal. Loses electrons Low electronegativity value Low ionization energy Large atomic radius Francium: The "Lower Left" Element -Fluorine is the most reactive nonmetal Gains electrons High electronegativity Value High ionization energy Small atomic radius - Fluorine is the opposite of Francium -As you go down a group each atom gains a electron shell (Principal energy level, orbital) and increase in atomic radius.

Ionic radius

-When a metal loses electron(s), the ion formed has a smaller radius than an atom of the same element. -When a nonmetal gains electron(s), the ion formed has a larger radius than an atom of the same element.

Electronegativity

-measure of an elements attraction for electrons on a scale of 0.7 - 4.0 -Francium(Fr) has the lowest electronegativity (0.7) It does not take electrons from atoms of other elements. Fluorine (F) has the highest electronegativity (4.0). It does take electrons from the atoms of other elements.

Nonmetals

Gain valence electrons from other atoms because they can take other atoms' electrons (high electronegativity) and they do not easily give up their own valence electrons (high ionization energy).

Metals

Lose their valence electrons to other atoms because they cannot take other atoms' electrons (low electronegativity) and they easily give up their own valence electrons (low ionization energy)

Staircase

Separates metal and nonmetal elements.

Group 17

The halogens Gases (Fluorine, chlorine) Liquid (Bromine) Solids (Iodine, astatine)

Valence shell

The most electrons in a valence shell is 8.

Group 18

The noble gases Have a stable electron configuration ending in 8 (Helium has a full 1st electron shell)

Valence

The outermost electron shell. The electrons in this shell are called valence electrons. Carbon has 4 valence electrons.

Main group elements

all have the same number of valence (outermost) shell electrons. For example, all the elements in Group 13 have 3 valence electrons. - Main group elements in the same group react similarly.

Main group elements

are groups 1,2, 13-18

Transition Elements

are groups 3-12

Elements

in the periodic table are arranged in order of increasing atomic number.