Metals

- Found on the left side of the periodic table

Includes: All of groups 1 (except H) and 2, also Al (but not B) in group 13.

All of the transition elements.

The elements to the right of the transition elements

The lanthanides and actinides (inner transition metals)

Metals tend to lose electrons!

Metallic Properties:

LusterLuster: most metals have a silvery white “metallic” color because they reflect light of all wavelengths.

Ductile,Ductile, (capable of being drawn out into a wire)

Malleable Malleable (can be hammered into thin sheets)

Most semisolidssemisolids @ room Tº

High electrical conductivity & thermal High electrical conductivity & thermal conductivityconductivity

- Examples: sodium, calcium, gold, aluminum

Nonmetals

• Found on the right side of the periodic table• Nonmetals tend to gain electrons!• Nonmetallic Properties:

– Poor reflectors of light,Poor reflectors of light,– Hard or brittle, some are gases or soft solidsHard or brittle, some are gases or soft solids– Not malleable or ductileNot malleable or ductile– Do not conduct electricity,Do not conduct electricity,– Poor conductor of heatPoor conductor of heat

- Examples: carbon, bromine, chlorine, sulfur

Metalloids or Semimetals

• Found along jagged line on table

• Metalloids lose or gain electrons depending on "who they're with!“

• Mixture of both types of properties, or intermediate type

Examples: B, Si, Ge, As, Sb, Te, At (the only metals on the solid "semimetal" line are

Al and Po)

Compounds and Chemical Reactions

Essentially all elements combine to form compounds

•Compounds are of two types:– Molecular, formed by shared electrons and

consist of electrically neutral, discrete particles called molecules

– Ionic – formed by electron transfer and charged particles called ions

Ionic Compounds – ionic crystals that can vary in size….

Molecular compounds – discrete

particles or molecules

• Chemical formulas are collections of chemical symbols that are used to describe elements and compounds

– Free elements are not combined with other elements in a compound

Examples: Fe (iron), Na (sodium), and K (potassium)

A chemical formula is a symbolic representation of the composition of a compound in terms of its constituent elements.

• Chemical formulas specify the composition of a substance

• NaCl is composed of the elements sodium and chlorine in a one-to-one (atom) ratio

• Fe2O3 is composed of the elements iron and oxygen in a two-to-three ratio

• CO(NH2)2 expands to CON2H4, but there are good reasons to write some compounds with parentheses

• Hydrates are crystals that contain water molecules, for example plaster: CaSO4 • 2H2O

– When all the water is removed (by heating), the solid that remains is said to be anhydrous (without water)

Ions and Ionic Compounds

Atoms that gain or lose electrons are called ions

Positive ions: CATIONS Negative ions: ANIONS

Atoms that lose electrons form cations

Na Na+ + e–

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Atoms that gain electrons form anions

Cl + e– Cl–

The charges on many representative elements can be predicted:

• Metals form cations– The positive charge on the cation is the same as the “A”

group number of the metal – Ask: “How many e- needed to lose to reveal noble gas

core?”

• Nonmetals form anions– The negative charge on the anion is equal to the number

of spaces to the right we have to move in the periodic table to get to a noble gas

– Ask: “How many e- needed to gain to make noble gas core?”

Ion Typically formed

Names and Formulas forIonic Compounds

Ionic compounds form when oppositely charged ions are attracted to each other NaCl

Resulting compound is electrically neutral

Na+ Cl–

(+1) + (–1) = 0

Ionic compound names use the cation name followed by the anion name

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Sodium chloride

Ionic Bonding is the TRANSFER of electrons from one element to another.

Polyatomic Ions

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Polyatomic ions are charged groups of covalently bonded atoms

• Rules for writing Formulas of Ionic Compounds:1) The positive ion is given first in the

formula.

2) The subscripts in the formula must produce an electrically neutral formula unit.

3) The subscripts should be the set of smallest whole numbers possible.

4) The charges on the ions are not included in the finished formula of the substance.

Introduction to Compounds

A molecule is a group of two or more atoms held together by covalent bondscovalent bonds.

Remember: Ionic Compounds form crystals. The term used for Ionic compounds is "formula unit“ not molecule!

http://astrobob.areavoices.com/files/2013/04/Water-molecule-panel-1024x409.jpg

In a Covalent BondCovalent Bond, atoms SHARE electrons to form stable pairs.

Many nonmetals occur as diatomic molecules

There are 7 elements that occur as diatomic molecules in nature:

Molecules that contain two atoms bonded together are called diatomic molecules.

Molecular Compounds

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Ball-and-stick model vs. Space-filling model

Empirical and Molecular Formulas

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Empirical formula:Empirical formula: the simplest whole number ratio of elements in a compound (covalently bonded)

Example: Molecular formula of glucose – C6H12O6

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The elemental ratio C:H:O is 1:2:1, so the empirical formula is CH2O

Molecular formula:Molecular formula: the actual number of atoms of elements in a compound

• Inorganic compounds are substances not considered to be derived from hydrocarbons and do not have carbon in them.

• The rules for naming, or nomenclature, of simple inorganic compound is covered now (organic nomenclature is covered later)

• Binary compounds are compounds comprised of two different elements

• The goal is to be able to convert between the chemical formula and the name

Formulas and Subscriptsin Molecules

Subscripts are used when a given atom is used more than once

e.g., H2O, CO2, N2O, HF, B2O3

The presence of The presence of subscripts is subscripts is reflected in the reflected in the names of compoundsnames of compounds

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Binary Molecular Compounds

Compounds that are typically comprised of two nonmetallic elements:

e.g., CO, NO, HF

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Molecular formulas are usually written with the more “metallic” first – “metallic” means farther left in the period and lower in the group

• The first element in the formula is identified by its English name, the second by appending the suffix –ide to its stem

Chemical Name as Name asSymbol Stem First Element Second Element O ox- oxygen oxide S sulf- sulfur sulfide N nitr- nitrogen nitride P phosph- phosphorus phosphide F fluor- fluorine fluoride Cl chlor- chlorine chloride Br brom- bromine bromide I iod- iodine iodide

• Many molecular compounds contain hydrogen:

Group NoblePeriod 14 15 16 17 Gas (18) 2 CH4 NH3 H2O HF Ne 3 SiH4 PH3 H2S HCl Ar 4 GeH4 AsH3 H2Se HBr Kr 5 SbH3 H2Te HI Xe

Note: The number of hydrogens that combined with the nonmetal equals the number of spaces to the right we have to move to get to the noble gas

• The number of each type of atom is specified with Greek prefixes

Greek Prefixes mono- = 1 (often omitted) hexa- = 6 di- = 2 hepta- = 7 tri- = 3 octa- = 8 tetra- = 4 nona- = 9 penta- = 5 deca- = 10

Examples: PF5 = phosphorus pentafluoride HCl = hydrogen chloride N2O5 = dinitrogen pentoxide

Note: many compounds have common names, like water for H2O.

Names of Binary Compounds

The names are further modified by adding prefixes to denote the numbers of atoms

Consider the compounds CO and CO2

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• To name a compound, you can use this flowchart: