Chapter 7 State Standards: 3.f; 7.a; 7.b; 7.c; 1Contreras

Chapter 7-1: The Periodic Table 2Contreras

The Periodic Table of Elements Dmitri Mendeleev (grouped according to increasing atomic mass) Lighter at top, heavier at bottom Periodic: happening at regular intervals Pattern that repeats every 7 elements (like the days of the week) Elements are arranged on the periodic table according to their atomic number and chemical properties 3Contreras

Classes of Elements Elements classified according to their properties as metals, nonmetals, and metalloids Electrons in outer energy level (valence electrons) help determine element’s category 4Contreras

Metals (green) Left of the zigzag line Few electrons in outer energy ring Most solid at room temperature Properties: shiny; ductile; malleable; good conductors electricity/thermal energy 5 (Green) Contreras

Nonmetals (orange) Right of the zigzag Almost complete set of electrons in outer level More than half are gases at room temperature Many have opposite properties of metals (ie- dull; brittle; poor conductors of electricity/thermal energy) 6 (Orange) Contreras

Metalloids (purple) Border the zigzag Also called semimetals About half complete set of electrons in outer level Properties of both metals and nonmetals Ex. Boron – hard like a diamond; very brittle; good conductor of electricity 7 (Purple) Contreras

Chemical Symbols Symbols usually one or two letters First letter always capitalized Other letters always lowercase Color of the chemical symbol indicates physical state of element at room temp. 8 Atomic number Chemical symbol Element name Atomic mass Contreras

Periods Each horizontal row from left to right on the periodic table Properties follow a repeating pattern Physical and chemical properties change across each period 9Contreras

Chapter 7-2: Grouping Elements 10Contreras

Groups Each vertical column from top to bottom on the periodic table Have similar chemical and physical properities Also called a family 11Contreras

Group 1: Alkali Metals 12 Group 1 Group Contains: Metals Valence Electrons: 1 Reactivity: Most reactive metals Can easily give away one electron from outer level Only found combined with other elements in nature Compounds have many uses Sodium chloride (table salt) Does not include Hydrogen! Contreras

Group 2: Alkaline-Earth Metals Group Contains: Metals Valence Electrons: 2 Reactivity: Very reactive Not as easy to give away 2 electrons when combining Cement, chalk, humans 13 Group 2 Contreras

Groups 3-12: Transition Metals Group Contains: Metals Valence Electrons: 1 or 2 Reactivity: Less reactive than alkaline-earth metals Also contain lanthanides and actinides Good conductors of thermal energy Ex. Mercury (thermometers), gold, titanium, iron 14Contreras

Group 13: Boron Group Group Contains: One metalloid & 5 metals Valence Electrons: 3 Reactivity: Reactive Ex. Aluminum 15 Group 13 Contreras

Group 14: Carbon Group Group Contains: One nonmetal, 2 metalloids & 3 metals Valence Electrons: 4 Reactivity: Varies Ex. Carbon - found in proteins, fats, carbohydrates, diamonds 16 Group 14 Contreras

Group 15: Nitrogen Group Group Contains: 2 nonmetals, 2 metalloids & 2 metals Valence Electrons: 5 Reactivity: Varies Nitrogen is 70% of air (not very reactive) Phosphorus extremely reactive (on box to light matches) 17 Group 15 Contreras

Group 16: Oxygen Group Group Contains: 3 nonmetals, 1 metalloid & 1 metal Valence Electrons: 6 Reactivity: Reactive Oxygen is 20% of air (necessary for things to burn) Sulfuric acid is most widely used compound in chemical industry 18 Group 16 Contreras

Group 17: Halogens Group Contains: nonmetals Valence Electrons: 7 Reactivity: Very reactive Only need to gain one electron to have full outer ring (almost complete set) Quick to combine with metals to form a salt 19 Group 17 Chlorine (gas) Bromine (liquid) Iodine (solid) Contreras

Group 18: Noble Gases Group Contains: nonmetals Valence Electrons: 8 Reactivity: Unreactive Full set of 8 electrons in outer level Sometimes called inert gases Argon used in light bulbs doesn’t react with hot metal filament 20 Group 18 Contreras

Hydrogen: A group of its own Valence Electrons: 1 Reactivity: Reactive Most abundant element in the universe One proton & one electron Reactive nature makes it useful as fuel for rockets 21 Hydrogen Contreras