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I. Elements, Compounds, and Mixtures

Element- simplest type of matter with unique physical and chemical properties.

Each Element consists of only one kind of atom

Each Element is unique b/c the properties of its atoms are unique Substance- matter whose composition is fixed

Molecule- type of matter composed of two or more different elements that are chemically bound together

Elements are present in fixed parts by mass (fixed mass ratio

Compound is also considered a substance

Properties are different from those of its component elements

Mixture- group of two or more substances that are physically intermingled (mixtures can vary in their parts by mass)is not a substance b/c its composition is not fixed

A mixture retains many of the properties of its components

Unlike compounds, can be separated into components by physical changesII. The Observations that led to an Atomic view of Matter

A. Mass Conservation- most fundamental chemical observation of the 18th century

Law of mass conservation- the total mass of substances does not change during a chemical reaction (# of substances can change, and properties have to, but total amount of matter is constant) *** matter cannot be created or destroyed

B. Definite Composition

Law of Definite (or constant) composition)- no matter what its source, a particular compound is composed of the same elements in the same parts by mass

Fraction by mass (mass fraction)- part of the compounds mass that each element contributes

Percent by mass (mass percentage)- fraction by mass expressed by a percentage

Mass of element in sample= mass of compound in sample x (mass of element in compound/ mass of compound)

C. Multiple Proportions

Dalton- law of multiple proportions- if elements A and B react to form two compounds, the different masses of B that combine with a fixed mass of A can be expressed as a ratio of small whole numbers

III. Daltons Atomic Theory

A. Postulates of the Atomic Theory

1. All matter consists of atoms

2. Atoms of one element cannot be converted into atoms of another element. In chemical reactions, the atoms of the original substances recombine to form different substances.

3. Atoms of an element are identical in mass and other properties and are different from atoms of any other element

4. Compounds result from the chemical combination of a specific ratio of atoms of different elements

B. How the Theory Explains Mass Laws

Mass conservation- postulate 1, 2 and 3does not allow for mass change

Definite composition- postulate 4 and 3fixed fraction of mass

Multiple proportions- postulate 1

IV. The Observations that Led to the Nuclear Atom Model

A. Discovery of the Electron and Its Properties

Cathode- negative electrode

Anode- positive electrode

Cathode ray- ray that could be seen striking the phosphor coated end of the glass tube

Cathode ray particles were later named electrons

1897-J.J. Thomson estimated the electron weighed less than 1/1000 as much aas hydrogenshocked because, according to this atoms are even further divisible

mass of electron- (-9.109x 10-28)

1909- Robert Millikan measured charge of the electron (-1.602 x 10-19)

B. Discovery of the Atomic Nucleus

Rutherford- (gold foil) an atom is mostly space occupied by electrons

Nucleus- tiny region in the center of atom that contains all positive charge and essentially all mass of the atom (99.97%) (1 quadrillionth of the volume)

1932- James Chadwick discovered neutron

V. The Atomic Theory Today

A. Structure of the Atom

B. Atomic Number, Mass Number, and Atomic Symbol- mass # is superscript, atomic number is subscript

C. Isotopes and Atomic Masses of the Elements-

all isotopes have nearly identical chemical behavior

amu is 1/12 the mass of a carbon-12 atom (1.66054x10-24)

mass spectrometry- method for measuring the relative masses and abundances of atomic-scale particles very precisely

isotopic mass- mass of isotope relative to the mass of the standard carbon-12 isotope

atomic mass- weighted average of masses of the naturally occurring isotopes

D. A Modern Reassessment of the Atomic Theory

VI. Elements: A First Look at the Periodic Table

Lavoisier- 23 elements

1870- 65 elements

1925-88 elements

1871 Dmitri Mendeleev published periodic table of elements

1. each element has a box w/ atomic number, symbol and atomic mass (boxes are in order of increasing atomic number)

2. periods are horizontal rows (1-7), groups are vertical columns (1-8 w/ either A or B)

3. 8A groups contain representative elements, 10 B groups are transition elements (bottom part, 2 horizontal series fit between 3B and 4B)

4. metals- shiny solids at room temp. (mercury is the only liquid), conduct heat and electricity well, can be tooled into sheets and wires

5. nonmetals- gases or dull brittle solids at room temp (bromine is only liquid), conduct heat and electricity poorly

6. metalloids- elements that have properties between those of metals and nonmetals

7. Organic chemistry- studies compounds of carbon (fuels, dyes, drugs, polymers)

8. Inorganic chemistry- compounds of all other elements

1A Alkali Metals (not hydrogen)

2A Alkaline Earth Metals

7A- Halogens

8A- Noble gases

3A(13)- 6A usu. Named for first element in group

VII. Compounds: Introduction to Bonding

Ionic compounds- transferring electrons from the atoms of one element to those of another

Covalent compounds- sharing electrons between atoms of different elements

Chemical bonds- forces that hold the atoms of elements together in a compound

A. The Formation of Ionic Compounds

Ion- charged particle that forms when an atom gains or loses one or more electrons

Binary ionic compound- ionic compound composed of just 2 elements

Cation- positively charged ion

Anion- negatively charged ion

Metal atoms electrons( nonmetal atoms

*** All binary ionic compounds are solids

monatomic ion- cation or anion derived from a single atom

the energy of attraction or repulsion between to particles is directly proportional to the product of the charges and inversely proportional to the distance between them Ionic compounds possess no net charge

Elements gain and lose electrons to form ions with as close to the same number of electrons as an atom of the nearest noble gas

B. The Formation of Covalent Compounds

Polyatomic ions- consist of two or more atoms bonded covalently and have a net positive or negative charge

C. The Elements of Life- page 63-64

VIII. Compounds: Formulas, Names, and Masses

A. Types of Chemical Formulas- element symbols and numerical subscripts

Empirical formula- relative number of atoms of each element in the compound

Molecular formula- actual number of atoms of each element

Structural formula- number of atoms and the bonds between them

B. Some Advice about Learning Names and Formulaspage 65

Members of a periodic group have the same ionic charge

A-group cations, ion charge= group #

Anions, ion charge= group # minus 8

C. Names and Formulas of Ionic Compounds

Formula unit- relative numbers of cations and anions in the compound

Oxoanions- those in which an element, usu. Nonmetal, is bonded to 1+ oxygen atomsrules bottom of pg. 68

Hydrates- have specific # of water molecules assoc. w/ each formula unit

binary acid- forms when gaseous compounds dissolve in water

oxoacidpage 69

D. Names and Formulas of Binary Covalent Compounds- formed by combo of 2 elements, usu. nonmetals

E. An Introduction to Naming Organic Compounds pg. 71

Hydrocarbons- have only hydrogen and carbon

Alkanes- kind of hydrocarbon, named with a root followed by suffix ane

F. Molecular Masses from Chemical Formulas

Molecular- made of molecules, so molecular mass

Formula mass- same as molecular, but for ionic compounds

IX. Mixtures: Classification and Separation

Homogenous mixturesolution

Aqueous solutions- solutions in water