Periodic Table Chemistry 4 th block

Alkaline Earth Metals Boron Group Carbon Group Nitrogen Group Oxygen Group

Alkali Metals  Comes from the arabic al aqali which means “the ashes”  Wood ashes are rich in compounds of the alkali metals sodium (Na) and potassium (K)  Most reactive metals because they only need to lose one electron to have a complete outermost orbital or shell  Readily lose their outermost electron to form cations with a 1+ charge

Alkaline Earth Metals  Readily lose their two outermost electrons to form cations with a 2+ charge

Halogens  Comes from the Greek word hals-meaning “salt” and the Latin word genesis- “meaning to be born”  Chlorine, Bromine and iodine can be prepared from their salts  Most reactive nonmetal elements because they are only missing one electron from their outermost orbital  Readily gain an electron to form anions with a -1 charge

Noble Gases  Rarely take part in a reaction because they have a complete outermost orbital or shell  Least reactive of the elements

Metals  Good conductors of heat and electric current  High luster  Solids at room temperature, except for Mercury (Hg)  Malleable- hammered into thin sheets

Nonmetals  Greater variation in physical properties than metals  Poor conductors of heat and electric current (with exception of Carbon)  Solid nonmetals tend to be brittle-shatter if hit with a hammer  Most are gases at room temperature  A few are solids like Sulfur and Phosphorus  Bromine- dark-red liquid

Metalloids  B-Boron, Si-Silicon, Ge-Germanium, As-Arsenic, Sb- Antimony, Te-Tellurium, At-Astatine  Has properties that are similar to those of metals and nonmetals

Reading the Periodic Table  The periodic table is a chart identifying each known type of atom (element). Element Name Average Atomic Mass Element Symbol Atomic Number

Element Symbols  When you write the symbol for an element make sure that you CAPITALIZE the 1 st letter of the symbol and lowercase the 2 nd letter (if there is one).  Examples: Li = Lithium, C = Carbon

Identifying Atoms in Compounds  Examples: H 2 O(dihydrogen monoxide/water)- hydrogen atoms and oxygen atoms NaCl (sodium chloride/ table salt)- Sodium atoms and Chlorine atoms CaCl 2 (Calcium Chloride)- Calcium atoms and chlorine atoms

Atomic Number  The number of protons in the nucleus of an atom of an element  Used to organize the elements on the periodic table

Isotopes  Atoms of the same element that have the same atomic number but different atomic masses due to a different number of neutrons

Isotopes (12*0.989)+(13*0.011)+(14* )=12.011

Isotopes of Hydrogen

Average Atomic Mass  The sum of the masses of the isotopes of an element, each multiplied by its natural abundance (the decimal form of the percent of atoms of that element that is a given isotope).  The mass found on the periodic table…almost all elements on the periodic table are in order of increasing average atomic mass. Some Exceptions: Ar and K, Co and Ni, Cu and Zn, Te and I  Not a whole number because it is an average of its isotopes

Mass Number  The mass number is equal to the number of protons plus the number of neutrons found in the nucleus.  Relates to a specific isotope

Ions  An atom or group of atoms that has a positive or negative charge, formed when electrons are transferred between atoms  If an atom has the same number of protons (+) and electrons (-) it is considered neutral because the charges cancel.

Molecules  Molecule-two or more atoms joined together chemically  Molecules are NOT always compounds  Compounds are always molecules  Remember compounds: a substance that contains two or more elements chemically combined in a fixed proportion  Remember Elements: the simplest form of matter that has a unique set of properties; an element cannot be broken down into simpler substances by chemical means  Ex: H 2 : Molecule & Element but NOT a compound  H 2 O: molecule or compound

7 Diatomic Molecules: Molecules Consisting of 2 Atoms  Have  H 2  No  N 2  Fear  F 2  Of  O 2  Ice  I 2  Cold  Cl 2  Baths  Br 2

7 Diatomic Molecules  Hydrogen, Nitrogen, Oxygen, Fluorine, Chlorine, Bromine and Iodine are never seen as an element by themselves  So reactive that they can be found very often bonded with another atom of the same type

Bohr Model Help Filling in Electrons n = 1 → 1s orbital → 2 electrons  TOTOAL 2 n = 2 → 2s orbital → 2 electrons → 2p orbital → 6 electrons  TOTAL 8 n = 3 → 3s orbital → 2 electrons → 3p orbital → 6 electrons → 3d orbital → 10 electrons  TOTAL 18 Beyond n = 4, all levels have s, p, d and f orbitals. n = 4 → 4s orbital → 2 electrons → 4p orbital → 6 electrons → 4d orbital →10 electrons → 4f orbital → 14 electrons  TOTAL 32