Chapter 7

State Standards:3.f; 7.a; 7.b; 7.c;

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Chapter 7-1: The Periodic Table

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The Periodic Table of ElementsDmitri Mendeleev (grouped according to

increasing atomic mass)Lighter at top, heavier at bottom

Periodic: happening at regular intervalsPattern 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

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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

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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

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(Green)

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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)

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(Orange)

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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

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(Purple)

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Chemical Symbols

Symbols usually one or two lettersFirst letter always capitalizedOther letters always lowercase

Color of the chemical symbol indicates physical state of element at room temp.

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Atomic number

Chemical symbol

Element name

Atomic mass

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PeriodsEach horizontal row from left to right on the

periodic tableProperties follow a repeating pattern

Physical and chemical properties change across each period

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Chapter 7-2: Grouping Elements

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GroupsEach vertical column from top to bottom on

the periodic table

Have similar chemical and physical properities

Also called a family

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Group 1: Alkali Metals

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Group 1Group Contains: MetalsValence Electrons: 1Reactivity: 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!

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Group 2: Alkaline-Earth MetalsGroup Contains: MetalsValence Electrons: 2Reactivity: Very reactive

Not as easy to give away 2 electrons when combining

Cement, chalk, humans

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Group 2

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Groups 3-12: Transition MetalsGroup Contains: MetalsValence Electrons: 1 or 2Reactivity: Less reactive than alkaline-earth

metalsAlso contain lanthanides and actinides

Good conductors of thermal energyEx. Mercury (thermometers), gold, titanium, iron

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Group 13: Boron GroupGroup Contains: One metalloid & 5

metalsValence Electrons: 3Reactivity: Reactive

Ex. Aluminum

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Group 13

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Group 14: Carbon GroupGroup Contains: One nonmetal,

2 metalloids & 3 metalsValence Electrons: 4Reactivity: Varies

Ex. Carbon - found in proteins, fats, carbohydrates, diamonds

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Group 14

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Group 15: Nitrogen GroupGroup Contains: 2 nonmetals,

2 metalloids & 2 metalsValence Electrons: 5Reactivity: Varies

Nitrogen is 70% of air (not very reactive)

Phosphorus extremely reactive(on box to light matches)

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Group 15

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Group 16: Oxygen GroupGroup Contains: 3 nonmetals, 1 metalloid &

1 metalValence Electrons: 6Reactivity: Reactive

Oxygen is 20% of air (necessaryfor things to burn)

Sulfuric acid is most widely used compound in chemical industry

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Group 16

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Group 17: HalogensGroup Contains: nonmetalsValence Electrons: 7Reactivity: Very reactiveOnly need to gain one electron to

have full outer ring (almost complete set)

Quick to combine with metalsto form a salt

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Group 17

Chlorine (gas)

Bromine (liquid)

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Group 18: Noble GasesGroup Contains: nonmetalsValence Electrons: 8Reactivity: 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

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Group 18

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Hydrogen: A group of its ownValence Electrons: 1Reactivity: Reactive

Most abundant element in the universe

One proton & one electron

Reactive nature makes it useful as fuel for rockets

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Hydrogen

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