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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 atoms All atoms of an element are alike No to elements have the same atoms - PowerPoint PPT Presentation
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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 alike2. No to elements have the same atoms3. Atoms cant be broken into smaller pieces4. Atoms combine to make compounds5. Every atom of an element has the same
mass6. 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 Gases
Gases 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?