THE PERIODIC TABLE

SCIENTISTS INVOLVED IN THE PERIODIC TABLE DEVELOPMENT Newlands—English scientist who first arranged elements according to increasing atomic mass (developed no table or chart) Found similar element properties every 7 spaces apart; later became 8 spaces apart after adding noble gases (AKA Law of Octaves)

Mendeleev—Russian chemist who arranged the known 63 elements based on increasing atomic mass so that elements with similar properties fell into the same column on his table; gaps in his table were elements that he predicted the properties of (Sc, Ga, Ge) Periodic—repeating according to a pattern (Ex: days of the week)

Ramsay—added the last column to Mendeleev’s table Moseley—British scientists who determined the atomic #s of elements using X-rays; he is who our modern table is based on

Periodic law States that an element’s chemical and physical properties are periodic functions of their atomic #s As you go across a period (series)—start with reactive metal solid and end with nonreactive (inert) nonmetal gas Going down a group (family)---elements have similar chemical and physical properties

http://www.open.edu/openlearn/science-maths-technology/science/chemistry/alkali-metals http://www.sciencegeek.net/Chemistry/chempdfs/PeriodicTrends.pdf

Metals Nonmetals Metalloids magnetic not Means “metal-like” Malleable AND Ductile brittle Have at least 1 side of its element box touching staircase (8 total because Al is a metal) Have luster dull White/gray in color Good conductor Good insulator AKA semi-conductors High corrosion Low corrosion High density Low density High melting pt./boiling pt. Low melting pt./boiling pt.

Form Positively charged cations Form Negatively charged anions Metals Nonmetals Lose electrons Gain electrons Form Positively charged cations Form Negatively charged anions Found left of the staircase line Found right of the staircase line React with acids to form hydrogen gas Do not

Element Families (Groups) Family/Group Name Characteristics Alkali metals (1A) Most reactive metal family (Francium is most reactive); have 1 valence electron; +1 oxidation number Alkaline earth metals (2A) Have 2 valence electrons; +2 oxidation number Transition Metals AKA “B” groups; have varying oxidation numbers Boron family (3A) Contains 1 metalloid and 4 metals; 3 valence electrons +3 oxidation number Carbon family (4A) Contains 1 nonmetal, 2 metalloids, & 2 metals; 4 valence electrons + and -4 oxidation number Nitrogen family (5A) 5 valence electrons; -3 oxidation number Oxygen family (6A) 6 valence electrons; -2 oxidation number Element Families (Groups)

Continued Halogens (7A) Most reactive nonmetal family (Fluorine is most reactive and has highest electronegativity); 7 valence electrons -1 oxidation number; Name means “Salt formers” in Greek Noble Gases AKA inert gases; Do not react to form compounds due to full valence electron shell All have 8 valence electrons (Except He) Lanthanide Series AKA Rare earth metals; belong in row 6 due to their atomic number (sometimes known as inner transition metals) Actinide Series Belong in row 7 due to their atomic number (sometimes known as inner transition metals); Are radioactive Continued

Representative Elements (Main Group Elements) All “A” groups because their “A” column number represents how many valence electrons they have Oxidation number---refers to how many valence electrons are lost or gained in order to bond Oxidation number pattern For “A” groups: +1, +2, +3, + and -4, -3, -2, -1, 0

Atoms vs. Ions Atoms Ions Are electrically neutral Can have positive or negative charge Protons = electrons Have lost or gained electrons Can be cations which are 1. positive 2. have lost electrons 3. are characteristic of metals 4. are smaller than the original atom Can be anions which are Negative Have gained electrons Are characteristic of nonmetals Are larger than the original atom

Practice Questions 1. Which is smaller: S-1 OR S-2 2. Which is smaller: Sn+2 OR Sn+4 3. Which is larger: Al OR Al+3 4. Which is larger: N-3 OR N