ATOMS AND MOLECULES

Atoms

Atoms are basic building blocks of matter.

Democritus- developed the theory that atoms made all matter in 450 B.C

Atoms

John Dalton- proposed the atomic theory of atoms1. All atoms of an element are alike

2. No to elements have the same atoms

3. Atoms cant be broken into smaller pieces

4. Atoms combine to make compounds

5. Every atom of an element has the same mass

6. The masses of atoms in a compound must be equalized Found not to be true

Atoms

J.J. Thompson- said atoms were a ball of positive charges with negative charges scattered throughout

Atoms Smallest unit of matter but not the

smallest particle of matter

Made of:○ Protons- have mass and a + charge○ Electrons- have very little mass and a

- charge○ Neutrons- have about the same mass as a

proton but have no charge

Atoms

Ruthorford- found the positively charged center of the atom called the nucleus (it contained + charged protons)

Niels Bohr

Father of the atomic model used today. Electron cloud

Cloud Model

Molecules

A molecule is the smallest particle of a substance that exists alone.

This is a picture of a water molecule. It is two parts hydrogen and one part oxygen.

    

              

Compounds

A compound is two or more elements combined together.

This is a picture of a salt compound.

Name the charge of each part of an atom (whether it’s negative or positive).ProtonNeutronElectron

Elements and the Periodic Table

Elements An element is

a substance made up of only one kind of atom.

Song

Classification is arranging items into groups or categories according to some criteria.

Classifying Matter

Review

Matter is usually defined as anything that has mass and occupies space.

Gas Liquid Solid

Total disorderLots of empty space

DisorderSome spaceParticles closertogether

OrderParticles fixed in position

Review

Solids, Liquids, and GasesGases have no defined shape or defined

volume○ Low density

Liquids flow and can be poured from one container to another○ Indefinite shape and takes on the shape of the

container.Solids have a definite volume

○ Have a definite shape.

Mixtures and Pure SubstancesA mixture has unlike parts and a composition that

varies from sample to sampleA heterogeneous mixture has two or more dislike

parts.A homogeneous mixture is the same throughout the

sample

A classification scheme for matter.

ReviewA physical change is a change that does

not alter the identity of the matter.A chemical change is a change that does

alter the identity of the matter.A compound is a pure substance that can

be decomposed by a chemical change into simpler substances with a fixed mass ratio

An element is a pure substance which cannot be broken down into anything simpler by either physical or chemical means.

Sugar (A) is a compound that can be easily decomposed to simpler substances by heating. (B) One of the simpler substances is the black element carbon, which cannot be further decomposed by chemical or physical means.

Elements

Names of ElementsThe first 103 elements have internationally accepted

names, which are derived from:○ The compound or substance in which the element was

discovered○ An unusual or identifying property of the element○ Places, cities, and countries○ Famous scientists○ Greek mythology○ Astronomical objects.

The elements of aluminum, Iron, Oxygen, and Silicon make up about 88 percent of the earth's solid surface. Water on the surface and in the air as clouds and fog is made up of hydrogen and oxygen. The air is 99 percent nitrogen and oxygen. Hydrogen, oxygen, and carbon make up 97 percent of a person. Thus almost everything you see in this picture us made up of just six elements.

MODERN ATOMIC THEORY

Chemical Symbols○ There are about a dozen common elements that

have s single capitalized letter for their symbol○ The rest, that have permanent names have two

letters.the first is capitalized and the second is lower

case.○ Some elements have symbols from their Latin

names.○ Ten of the elements have symbols from their Latin

or German names.

SymbolAtomic Mass

Atomic NumberCharge (if ion)

EXAMPLE

How many protons, neutrons and electrons are found in an atom of

13355 Cs

Atomic number = protons and electronsThere are 55 protons and 55 electrons

Mass number = sum of protons and neutrons133 – 55 = 78There are 78 neutrons

HHydrogen

1

1

Protons: Neutrons: 0Electrons:

NaSodium

23

11 Protons: 11Neutrons: Electrons:

Rhenium isotope

Re187

75Protons: 75Neutrons: 112Electrons: 75

The Periodic Law

Things to look forExplain the properties of metals.What are the noble gasses?What makes a metalloid different from a

non- metal?How do you calculate the atomic mass of an

element? What are the locations of the alkali

metals, the earth metals, the halogens, and the noble gasses?

The Periodic LawSimilar physical and chemical properties recur

periodically when the elements are listed in order of increasing atomic number.

The Modern Periodic Table

IntroductionA row is called a periodA column is called a group

Chemical “Families”IA are called alkali metals because the react with water

to form an alkaline solutionGroup IIA are called the alkali earth metals because

they are reactive, but not as reactive as Group IA.○ They are also soft metals like Earth.

Group VIIA are the halogens○ These need only one electron to fill their outer shell○ They are very reactive.

Group VIIIA are the noble gases as they have completely filled outer shells○ They are almost non reactive.

Four chemical families of the periodic table: the alkali metals (IA), the alkaline earth metals (IIA), halogens (VII), and the noble gases (VIIIA).

Alkaline metals- very reactive Earth metals- reactive Halogens- slightly reactive Noble gases- unreactive

Metal: Elements of the left side of the periodic table that are usually solids at room temperature, conduct heat, can be bent, and are shiny.

Non-Metal: Elements in the upper right corner of the periodic Table. Relatively unreactive

Metalloid: Elements that lie on a diagonal line between the Metals and non-metals. Their chemical and physical properties are intermediate between the two.

Conductive , brittle, solid, slightly reactive

Properties of Metals

Malleable- can be bent, hammered, and rolled

Ductile- can be drawn into strands

Magnetic

Review Horizontal rows are called periods Atomic number is the number of protons Atomic mass is the number of protons +

neutrons (average) Mendeleev made the first periodic table Chemical symbols are made of 1-2 letters Neutrons have no charge Electrons have a negative charge Shared Electrons are the electrons shared

between two atoms that are combined

Ticket Out

Choose One of the following questions to answer

Explain the properties of alkali metals, and where are they located?

What are the noble gasses, and where are they located?

What makes a metalloid different from a non- metal?

How do you calculate the atomic mass of an element?