the periodic table alkali metalsalkaline earthstransition metalshalogensnoble gases lanthanides and...

The Periodic tableAlkali Metals

Alkaline Earths

Transition Metals

Halogens

Noble Gases

Lanthanides and Actinides

Main Group

Main Group

Experimentation and Measure

Measurement is the comparison of a physical quantity to be measured with a unit of measurement-that is a fixed standard of measurementMeasurement of Matter: SI (Metric) Units~ is a decimal system. Quantities differing from the base unit by powers of ten are noted by the use of prefixes.

Table 1 The seven fundamental units of measurePhysical quantity Name of unit AbbreviationMass kilogram kgLength meter mTemperature Kelvin KAmount of substance mole molTime second sElectric current ampere ALuminous intensity candela cd_______

Table 3 Some SI Prefixes

Multiple Prefix__ Symbol__

1015 peta P

1012 tera T

109 giga G

106 mega M

103 kilo k

102 hecto h

10 deca da

10-1 deci d

10-2 centi c

10-3 milli m You need to memorize the most

10-6 micro common SI prefixes such as G,

10-9 nano n M, k, d, c, m, , n and p.

10-12 pico p

10-15 femto f_______

Atoms, Molecules

and Ions

Early Discoveries

Lavoisier 1774 Law of conservation of mass

Proust 1799 Law of definite proportion

Dalton 1803-1888 Atomic Theory

Dalton’s Atomic Theory

Each element is composed of small particles called atoms.

Atoms of same element have same mass, but atoms of different

elements have different masses.

All atoms of a given element are identical

Compounds are formed when atoms of more than one element

combine

Consequences of Dalton’s theory

In forming carbon monoxide, 1.33 g of oxygen combines with 1.0 g of carbon.

In the formation of hydrogen peroxide 2.66 g of oxygen combines with 1.0 g of hydrogen.

Law of Definite Proportions: combinations of elements are in ratios of small whole numbers.

Behavior of charges

Cathode ray tube (Thomson’s Experiment)

Properties of cathode rays

Electron m/e = -5.6857 x 10-9 g coulomb-1

Charge on the electron

From 1906-1914 Robert Millikan showed ionized oil drops can be balanced against the pull of gravity by an electric field.

The charge is an integral multiple of the electronic charge, e.

The nuclear atom

Rutherford, 1909

The -particle experiment

Most of the mass and all of the positive charge is concentrated in a small region called the nucleus .

There are as many electrons outside

the nucleus as there are units of positive charge on the nucleus

The nuclear atom

Rutherfordprotons 1919

James Chadwickneutrons 1932

Atomic Diameter 10-8 cm Nuclear diameter 10-13 cm

Nuclear Structure

Particle Mass Chargekg amu Coulombs (e)

Electron 9.109 x 10-31 0.000548 –1.602 x 10-19 –1Proton 1.673 x 10-27 1.00073 +1.602 x 10-19 +1Neutron 1.675 x 10-27 1.00087 0 0

1 Å

Isotopes, atomic numbers and mass numbers

To represent a particular atom we use the symbolism:

A= mass number Z = atomic number

Ionic and Covalent bonding

Bond Formation

• The positive sodium ion and the negative chloride ion are strongly attracted to each other.

How Elements BondHow Elements Bond

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• This attraction, which holds the ions close together, is a type of chemical bond called an ionic bond.

Valence Electrons are…?

• The electrons responsible for the chemical properties of atoms, and are those in the outer energy level.

• Valence electrons - The s and p electrons in the outer energy level

– the highest occupied energy level• Core electrons – are those in the energy

levels below.

Keeping Track of Electrons• Atoms in the same column...

1) Have the same outer electron configuration.

2) Have the same valence electrons.

• The number of valence electrons are easily determined. It is the group number for a representative element

• Group 2A: Be, Mg, Ca, etc.– have 2 valence electrons

Electron Dot diagrams are…• A way of showing & keeping

track of valence electrons.

• How to write them?

• Write the symbol - it represents the nucleus and inner (core) electrons

• Put one dot for each valence electron (8 maximum)

• They don’t pair up until they have to (Hund’s rule)

X

Ionic Bonding

• Anions and cations are held together by opposite charges (+ and -)

• Ionic compounds are called salts.• Simplest ratio of elements in an ionic

compound is called the formula unit.• The bond is formed through the transfer

of electrons (lose and gain)• Electrons are transferred to achieve noble

gas configuration.

Bond Formation• The compound sodium chloride, or table

salt, is formed.

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• A compound is a pure substance containing two or more elements that are chemically bonded.

Ionic Compounds

1) Also called SALTS

2) Made from: a CATION with an ANION (or literally from a metal combining with a nonmetal)

More Gains and Losses• Can elements lose

or gain more than one electron?

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• The element magnesium, Mg, in Group 2 has two electrons in its outer energy level. • Magnesium can lose these two electrons and achieve a completed energy level.

More Gains and Losses

• Some atoms, such as oxygen, need to gain two electrons to achieve stability.

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• The two electrons released by one magnesium atom could be gained by a single atom of oxygen.

• When this happens, magnesium oxide (MgO) is formed.

Ionic Bonding

• All the electrons must be accounted for, and each atom will have a noble gas configuration (which is stable).

Ca P

Lets do an example by combining calcium and phosphorus:

Ionic Bonding

Ca P

Ionic Bonding

Ca2+ P

Ionic Bonding

Ca2+ P

Ca

Ionic Bonding

Ca2+ P 3-

Ca

Ionic Bonding

Ca2+ P 3-

Ca P

Ionic Bonding

Ca2+ P 3-

Ca2+ P

Ionic Bonding

Ca2+ P 3-

Ca2+ P

Ca

Ionic Bonding

Ca2+ P 3-

Ca2+ P

Ca

Ionic Bonding

Ca2+ P 3-

Ca2+P

3-

Ca2+

Convalent Bonds—Sharing

• Some atoms are unlikely to lose or gain electrons because the number of electrons in their outer levels makes this difficult.

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• The alternative is sharing electrons.

The Convalent Bond• The chemical bond that forms between

nonmetal atoms when they share electrons is called a covalent bond.

How Elements BondHow Elements Bond

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The Convalent Bond

• Shared electrons are attracted to the nuclei of both atoms.

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• They move back and forth between the outer energy levels of each atom in the covalent bond.

• So, each atom has a stable outer energy level some of the time.

The Convalent Bond• The neutral particle is formed when atoms

share electrons is called a molecule

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The Convalent Bond

How Elements BondHow Elements Bond

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• You can see how molecules form by sharing electrons in this figure.

Review of Chemical BondsReview of Chemical Bonds• There are 2 forms of bonding:There are 2 forms of bonding:

• __________________—complete —complete transfer transfer of 1 or more electrons of 1 or more electrons from one atom to another (one loses, the other gains) from one atom to another (one loses, the other gains) forming oppositely charged ions that attract one anotherforming oppositely charged ions that attract one another

• __________________——some valence electrons some valence electrons sharedshared between between atomsatoms

• __________________ – holds atoms of a metal together – holds atoms of a metal together