Chapter 3 – Classification of Matter

Elements – Distribution, Names, SymbolsElements - Metals, Nonmetals, MetalloidsDiatomic MoleculesChemical FormulasMixtures

Element:Element: A substance that cannot be A substance that cannot be decomposed into simpler substances by decomposed into simpler substances by chemical means.chemical means.

ElementsElements

Make up our Make up our chemical chemical alphabet.alphabet.

Over 100 Over 100 known known elementselements

Element:Element: Our building block of all substances. Our building block of all substances. Numbered in order of increasing complexityNumbered in order of increasing complexity

ElementsElements

•Elements through 92 are known to occur in nature. [with 4 exception Technetium (43), Promethium (61), Astatine (85), Francium (87)]•Above 92 only Plutonium (94) occur in nature.•Above 92 all elements must be synthesized in the laboratories in small quantities

Elements

Most substances can be decomposed into two or more simpler substance.

Water = Hydrogen and OxygenSugar = Carbon, Hydrogen, and

OxygenSalt = Sodium and Chloride

Elements

The smallest particle of an element that can exist is an atom, which is also the smallest unit of an

element that can enter into a chemical reaction.

Atoms are made up of subatomic particles that will be discussed later in the semester.

Distribution of ElementsElements are distributed unequally in nature

Ten elements make up 99% of the mass of the Earths Crust, seawater, and atmosphere

Oxygen is about 50% of this massTwo elements are liquids at room

temperature Bromine and Mercury

Eleven elements are gases Hydrogen, Nitrogen, Oxygen, Fluorine, Chlorine,

Helium, Neon, Argon, Krypton, Xenon, and Radon

All other elements are solids

Distribution of Elements

Elements are distributed unequally in nature Figure a, shows

the distribution in the glalaxies

Figure b, shows the distribution in Earths crust

Figure c, shows the distribution in Humans

Famous-Scientists

• Einsteinium: named for Albert Einstein.

Location • Germanium: discovered in 1866 by a German chemist.

German-Color

• Bismuth: from the German weisse mass which means white mass.

Greek-Color

• Iodine: from the Greek iodes meaning violet.

Latin-Property

• Fluorine: from the Latin fluere meaning to flow. The fluorine containing ore fluorospar is low melting.

Sources of Element Names

Symbols of the Elements

Each element has an abbreviation. Iodine is taken from Greek work iodes, meaning violet. Bismuth is from German, weisse masse, white mass. Germanium is due to it’s discovery by a German Others are named in commemoration of famous

scientist

Symbols of the ElementsEach element has an abbreviation –

Symbols Some (14) have single letterThe rest have 2 letters

The symbol stands for the element itself For one atom of the element For a particular quantity of the element

Rules. Symbols have either one or two letters If one letter – Capitalized If two letters – First letter capitalized – second

letter lower case

Ne neon

Rules governing symbols of the elements are:

1. Symbols have either one or two letters.

2. If one letter is used it is capitalized.

3. If two letters are used, only the first is capitalized.

H hydrogenC carbon

Ba barium

Symbols of the ElementsSymbols and names are on the inside cover.Possibly make flash cards to learn these symbols.

Metal, Nonmetals, and Metalloids

Metal, Nonmetals, and MetalloidsMetals

Most of the elements are metalsSolids at RT (except mercury)Malleable – Can be hammered or rolled into sheets.Ductile – Can be Drawn into wiresHigh Melting pointHigh densityCombine with non-metals to form ionic compoundsOften found as alloys – Homogenous mixtures

Metal, Nonmetals, and Metalloids

A few of the less reactive metals such as copper, silver and gold are found in the free state.

Metals can mix with each other to form alloys.

Brass is a mixture of copper and zinc. Bronze is a mixture of copper and tin. Steel is a mixture of carbon and iron.

Metal, Nonmetals, and Metalloids

NonmetalsLow melting points and densityGenerally poor conductors of heat and conductivityCombine with one another to form molecular compounds

MetalloidsProperties are intermediate between metals and nonmetals Some are raw material for semiconductor

boron silicon germanium arsenic antimony tellurium polonium

Metalloids

CompoundsCompounds

Compound:Compound: A substance with a A substance with a constant composition that can be constant composition that can be broken down into elements by broken down into elements by chemical processes.chemical processes. Atoms in a compound are always Atoms in a compound are always whole number ratioswhole number ratios Two types - molecular and ionicTwo types - molecular and ionic

Compounds

Molecule – The smallest uncharged individual unit of a compound formed from 2 or more atoms

Ion – Positively or negatively charged atom or group of atoms.Held together by attractive forces from

positively and negatively charged ions Cation – Positively charged Anion – Negatively charged

Compounds can be classified as molecular or ionic. Ionic compounds are held together by attractive forces between their positive and negative charges. Molecular compounds are held together by covalent bonds.

Diatomic Molecules Special type of molecule Contain 2 atoms – alike or different Seven elements are diatomic molecules

Hydrogen - H2 Oxygen - O2

Nitrogen - N2 Fluorine - F2 Chlorine - Cl2 Bromine - Br2 Iodine - I2

Need to know these!!!!

Hydrogen HNot found in nature.

Hydrogen H2

Found in nature.

Nitrogen NNot found in nature.

Nitrogen N2

Found in nature.

Occurrence of Diatomic Molecules

Chemical Formulas

Used as abbreviations for compounds Shows the symbols and the ratio of the elements

in a compound

H2O Indicates 2 Hydrogens and one Oxygen

H2SO4 Indicates 2 Hydrogens, 1 Sulfur, and 4 Oxygen

Water has the formula H2O.

H2 O2 H2O

• It does not contain free hydrogen, H2 or free oxygen, O2.

• The H2 part of H2O means that 2 atoms of hydrogen are combined with one atom of oxygen in the water molecule.

Serve as abbreviations of the names of compounds.

CaCl2calciumchloride

chemicalformulas

chemicalformulas

Tell which elements the compound is composed of and how many atoms of each element are present in a formula unit.

CaCl2calciumchlorine

chemicalformulas

Show the symbols of the atoms of the elements present in a compound.

CaCl2Ca calciumCl chlorine

chemicalformulas

Show the ratio of the atoms of the elements present in a compound.

2 Cl1 Ca

CaCl2

Chemical Formulas Formula of a compound contains the symbols of

all the elements Formula contains one atom of an element the

number 1 subscript is left out Formula contains more than one atom of the

same element – the number is indicated as a subscript written to the right of the symbol of that atom

When a formula contains more than one group of atoms occur as a unit – a parentheses is place around the group with the number subscripted Ca(NO3)2

indicates 3 H atoms

indicatesthe element phosphorous (P)

indicatesthe element hydrogen (H)

indicatesthe element oxygen (O)H3PO4

indicates 4 O atoms

Chemical Formulas

Ba3(PO4)2

indicates three Ba atoms

3-4phosphate (PO )

indicates two

groups

indicatesthe element barium

indicates the phosphate group composed of one phosphorous atom and four oxygen atoms

Chemical Formulas

Formulas written as H2O, H2SO4, Ca(NO3)2 and C12H22O11

show only the number and kind of each atom contained in the compound; they do not show the arrangements of the atoms in the compound or how they are chemically bonded to each other.

Chemical Formulas

Concepts - Chapter 3

Classify – elements, compounds, mixtures Write symbols or name for common elements Understand chemical formulas Differentiate between atoms, molecules, ions Know some characteristics of metals,

nonmetals and metalloids Recognize elements that occur as diatomic

molecules