TEK 8.5 Matter and energy.

The student knows that matter is composed of atoms and has

chemical and physical properties.

The student is expected to:A) Describe the structure of atoms, including the masses, electrical charges, and locations, of protons and neutrons in the nucleus and electrons in the electron cloud.B) Identify that protons determine an element’s identity and valence electrons determine its chemical properties including reactivity.C) Interpret the arrangement of the Periodic Table, including groups and periods, to explain how properties are used to classify elements.

D) Recognize that chemical formulas are used to identify substances and determine the number of atoms of each element in chemical formulas containing subscripts.

E) Investigate how evidence of chemical reactions indicate that new substances with different properties are formed.

F) Recognize whether a chemical equation containing coefficients is balanced or not and how that relates to the law of conservation of mass.

Vocabulary

AtomElementSubatomic particle NeutronProtonElectronAtomic Theory

John DaltonJJ ThomsonErnest RutherfordNeils BohrErwin SchrodingerLouis de Broglie

Atomic Structure Notes

Element

-substances that are the building blocks of all matter

-made up of one kind of atom-Ex. Carbon, Hydrogen, Oxygen

Atom

-The smallest particle into which an element can be divided and still maintain the properties of the element.

-made up of sub-atomic particles

Subatomic Particles

3 main structures1. Protons 2. Neutrons3. Electrons

Protons (+)

• particles found in the nucleus of an atom.

• have a positive charge

Neutrons

• Particles found in the nucleus of an atom.

• Have a neutral charge

Electrons (e-)

• Particles found in the electron cloud (orbiting the nucleus)

• Negatively charged

AMUs

-atomic mass unit aka Dalton

-used to describe the mass of subatomic particles

-equal to 1.660538921×10−27 kg

Sizes of Subatomic Particles

Protons Neutrons Electrons

1 AMU 1 AMU

.0005 AMU

Modeling Parts of an Atom

parts of an atom.

Nucleus

Electron Cloud

Nucleusmakes up 99.99%of atomic mass

Atomic Theory

-a scientific theory of the nature of matter, which states that matter is composed of discrete units called atoms.

Democritus

-influential pre-Socratic philosopher-formulated an atomic theory-400 B.C.

John Dalton

Solid Ball +1803

JJ Thomson

Plum pudding1897

Plum Pudding ModelAka

Muffin ModelAka

Arroz con Leche Model

Discovered Electrons

Ernest RutherfordPlanetary Model1909

Discovered Protons

Neils Bohr

Proton

Neutron

Electron

Nucleus

1913

Louis de Broglie & Erwin Schrodinger

Electron Cloud Model 1926

1927 Solvay Conference

PERIODIC TABLEAtoms Part II

VocabularyAtomic NumberAtomic MassAtomic SymbolValence electron

OrbitalElectron ShellEnergy LevelValence shell

Atomic Number

-reflects the # of protons in the nucleus and electrons in the electron cloud of a balanced atom of that element.

ATOMIC NUMBER = # OF PROTONS & ELECTRONS

Atomic Number

Atomic Mass

-the sum of the protons and the average number of neutrons

Atomic Mass

# of Neutrons

Np+-AM =

Atomic Mass (rounded to nearest whole number) minus # of protons

AM-P=N Example

Atomic Symbol

Putting it all together

Atomic Number

Element Symbol

Atomic Mass

Electron Orbitalsaka

Electron Shellsaka

Energy Levels

-the amount of energy carried by an electron in an atom

-determines the electron’s average distance from the nucleus

Energy Levels

Nucleus 2 e-

8 e-

8 e-

Nucleus

Valence Shell

-the outermost shell of an atom in its uncombined state-all atoms want their valence shells filled.

Valence Electron• electrons located in the valence shell• # of valence e- will determine the

reactivity of the atom.• The more Valence e’s the more stable and HAPPY (Nole Gases)

• The less valence e’s the more reactive and EXPLOSIVE or UNHAPPY (Alkali Earth Metals)