The Periodic table Alkali MetalsAlkaline EarthsTransition MetalsHalogensNoble Gases Lanthanides and Actinides 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 measurement Measurement 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 measure Physical quantityName of unitAbbreviation Masskilogram kg Lengthmeter m TemperatureKelvin K Amount of substancemole mol Timesecond s Electric currentampere A Luminous intensitycandela cd_______

Table 3 Some SI Prefixes MultiplePrefix__Symbol__ petaP teraT 10 9 gigaG 10 6 megaM 10 3 kilok 10 2 hectoh 10decada decid centic millimYou need to memorize the most micro  common SI prefixes such as G, nanon M, k, d, c, m, , n and p picop femtof_______

Atoms, Molecules and Ions

Early Discoveries Lavoisier 1774Law of conservation of mass Proust 1799Law of definite proportion Dalton 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 = x g coulomb -1

Charge on the electron  From 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 Rutherford protons 1919 James Chadwick neutrons 1932

Atomic Diameter cm Nuclear diameter cm Nuclear Structure ParticleMassCharge kgamuCoulombs(e) Electron x –1.602 x –1 Proton x x Neutron x Å

Isotopes, atomic numbers and mass numbers  To represent a particular atom we use the symbolism: A= mass numberZ = 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 Bond 2 2 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. How Elements Bond 2 2 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? How Elements Bond 2 2 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. How Elements Bond 2 2 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). CaP Lets do an example by combining calcium and phosphorus:

Ionic Bonding CaP

Ionic Bonding Ca 2+ P

Ionic Bonding Ca 2+ P Ca

Ionic Bonding Ca 2+ P 3- Ca

Ionic Bonding Ca 2+ P 3- Ca P

Ionic Bonding Ca 2+ P 3- Ca 2+ P

Ionic Bonding Ca 2+ P 3- Ca 2+ P Ca

Ionic Bonding Ca 2+ P 3- Ca 2+ P Ca

Ionic Bonding Ca 2+ P 3- Ca 2+ P 3- Ca 2+

Convalent Bonds—Sharing Some atoms are unlikely to lose or gain electrons because the number of electrons in their outer levels makes this difficult. How Elements Bond 2 2 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 Bond 2 2

The Convalent Bond Shared electrons are attracted to the nuclei of both atoms. How Elements Bond 2 2 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 How Elements Bond 2 2

The Convalent Bond How Elements Bond 2 2 You can see how molecules form by sharing electrons in this figure.

Review of Chemical Bonds There are 2 forms of bonding:There are 2 forms of bonding: _________—complete transfer of 1 or more electrons from one atom to another (one loses, the other gains) forming oppositely charged ions that attract one another_________—complete transfer of 1 or more electrons from one atom to another (one loses, the other gains) forming oppositely charged ions that attract one another _________—some valence electrons shared between atoms_________—some valence electrons shared between atoms _________ – holds atoms of a metal together_________ – holds atoms of a metal together