Introductory Chemistry, 3rd EditionNivaldo Tro

Electrons in Atomsand the

Periodic Table

2

Chapter 4

Recap of the Periodic Table

Tro's Introductory Chemistry, Chapter 9

Three Types of Elements

= Metal

= Metalloid

= Nonmetal

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Metals

Solids at room temperature, except HgShinyConduct heat, electricityMalleable: can be shapedDuctile = drawn or pulled into wiresLose electrons and form cations (+ charge) in reactionsAbout 75% of the elements are metals

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Nonmetals

Found in all 3 states

Poor conductors of heat & electricity

Solids are brittle

Gain electrons in reactions to become anions (- charge)Only a few on the right of periodic table

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Metalloids

Show some properties of metals and some of nonmetals

Also known as semiconductors Properties of Silicon

shinyconducts electricity

does not conduct heat wellbrittle

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The Modern Periodic Table

Elements with similar chemical and physical properties are in same column

Columns are called Groups or Families– designated by a number and letter at top

Rows are called Periods

Each period shows the pattern of properties repeated in the next period

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The Modern Periodic Table

Main Group = Representative Elements = ‘A’ groupsTransition Elements = ‘B’ groups– all metals

Bottom rows = Inner Transition Elements = Rare Earth Elements– metals– really belong in Period 6 & 7

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= Alkali Metals

= Alkali Earth Metals

= Noble Gases

= Halogens

= Lanthanides

= Actinides

= Transition Metals

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Important Groups - Hydrogen

nonmetal

colorless, diatomic gas– very low melting point & density

reacts with nonmetals to form molecular compounds– HCl is acidic gas– H2O is a liquid

reacts with metals to form hydrides– metal hydrides react with water to form H2

HX dissolves in water to form acids

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Important Groups – IA, Alkali Metals

hydrogen usually placed here, though it doesn’t belongsoft, low melting points,low densityvery reactive, never find uncombined in naturetend to form water soluble compoundsreact with water to form basic (alkaline) solutions and H2 releasing a lot of heat

lithium

sodium

potassium

rubidium

cesium

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Important Groups – IIA, Alkali Earth Metals

harder, higher melting, and denser than alkali metals

reactive, but less than corresponding alkali metal

form stable, insoluble oxides from which they are normally extracted

oxides are basic = alkaline earth

magnesium

calcium

beryllium

strontium

barium

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Important Groups – VIIA, Halogens

nonmetals

F2 & Cl2 gases; Br2 liquid; I2 solid

all diatomic

very reactive

react with metals to form ionic compounds

HX all strong acids except HF

bromine

iodine

chlorine

fluorine

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Important Groups – VIIIA, Noble Gases

all gases at room temperature, – very low melting and

boiling points

very unreactive, practically inert

very hard to remove electron from or give an electron to