Empedocles, a Greek philosopher active around 450 B. C Empedocles, a Greek philosopher active around 450 B.C. proposed 4 fundamental substances, fire, water, air ,earth. Formulating the idea of elemental substances

Democritus, 420 B.C. wrote that all matter was made up of small, indivisible particles he termed “atoms”.

3. Law of multiple proportions

4. In a chemical reaction – atoms move around and may change their order with respect to one another but, the atoms themselves don’t change

Pure substances can be a single atoms or ions or compounds with definite formulas

Separation of mixtures physical filtration

Separation of Homogeneous mixtures Distillation Thin Layer Chromatography

Law of Conservation of Mass Mass cannot be created nor can it be destroyed An automobile holds 21 kg of gasoline. When the gasoline burns 84 kg of oxygen is consumed, and carbon dioxide and water are produced. What is the total combined mass of carbon dioxide and water that is produced?

Law of Multiple proportions Upon decomposition, one sample of magnesium fluoride produced 1.65 kg of magnesium and 2.57 kg of fluorine. A second sample produced 1.32 kg of magnesium. How much fluorine (in grams) did the second sample produce?

Millikan discovered the charge on an electron using the oil drop experiment

Discovery of the neutron, Chadwick

Particle Mass in grams Charge in Coulombs Unit charge Electron 9.1x10-28 -1.6x10-19 -1 Proton 1.67x10-24 +1.6x10-19 +1 neutron

Fluorine atom Bohr model

Bohr model of gold atom How many electrons?

notation

Fluoride ion

Write notations for the following a. Iodine-127 ( number denotes A) b. Aluminum-27 (3+ cation) c. Sulfur-32 (2- anion)

Splitting the atom Atoms lose their physical properties that make them unique Large amounts of energy released Binding energy : energy that binds subatomic particle together

Isotopes: atoms with the same number of protons but different number of neutrons

All isotopes of the same element have the same atomic number

Mass spectrometer stick diagram for Boron

For the previous slide 1. if there is 5.0 g 202Hg in the sample How many grams of 198 Hg is in the sample? How many grams of 204 Hg is in the sample?

Average atomic mass

Average atomic mass example problems Three naturally occurring isotopes of magnesium have masses of 23.98504, 24.98584, and 25.98259 u. Their abundances are 78.70%, 10.13%, and 11.17% respectively. Calculate the chemical atomic weight of magnesium.

Average atomic mass practice exercise Gallium has two naturally occurring isotopes 69Ga and 71Ga with masses of 68.9257 amu and 70.9249 amu, respectively. Calculate the percent abundances of these isotopes of Gallium.

Periodic table

Metals and non metals

Groups and Periods

Groups numbers and names

Halogens group 7 Reactive Form anions Depending on the element can be Gas, liquid or solid at room temperature

Noble (Inert gases) Group 8 Only Xenon reacts, have 8 electrons in valence shell, all are gases at RT

Predictable monatomic charges