# The Atom and Periodic Table - Mr. Pate's Science Classes

The Atom and Periodic Table Physical Science Element verse Atom ELEMENT A substance that cannot be broken

down into simpler substances Ex: Neon, Gold, Helium ATOM Smallest particle of an element Counting unit of elements

History of the Atomic Model Democritus --believed in the atom John Dalton --made the theory on atoms J.J. Thomson

--found the electron Ernest Rutherford --found the nucleus History of the Atomic Model Neil Bohr --established energy levels

Electron Cloud Model --the current model of the atom 3 Subatomic Particles Atoms can be broken into: Protons Positively charged Symbol = p+

Mass = 1 Neutrons No charged (neutral) Symbol = n Mass = 1 Electrons Negatively charged Symbol = e Extremely small mass

Parts of an Atom Nucleus Center of the atom Small, dense, positively charged Where Protons and Neutrons remain Energy Levels/Shells/Orbitals

Around the nucleus Contains the electrons Atomic Number The Identify of the element Number of Protons Top of the Element Block SECRET: Also the

number of electrons Mass Number The sum of the Protons and Neutrons Bottom Number of the element block Round to the Nearest Whole

Number Understanding an Element Block ATOMIC NUMBER Element Symbol Element Name

1st letter is upper case 2nd letter is lower case Mass NUMBER How do you Find Items

Number of Protons = Atomic Number Number of Electrons = Number of Protons (Because Atoms are neutral which means positive equals negative) Number of Neutrons = Mass Number subtract Atomic Number Electron, Protons, Neutrons Example Practice Name

NEON BORON Symbol Atomic Number

Mass Number Number Number of Protons of Electrons Number of

Neutrons ISOTOPES Atoms of the same element that have the same atomic number but different mass numbers # of protons stays the

same # of neutrons change How Isotopes are Written Elements name/symbol dash mass number Ex: Oxygen16 p +=

n= Oxygen17 p += n= O18

p+= n= Why is Mass Number a Decimal? Mass Number is the weighted average of all the isotopes of an atom The isotope whom mass number is closest

to the actual mass number is more abundant IONS Charged Particles Negative Charge = gains electrons Positive Charge = lose electrons The Periodic Table

An arrangement of elements in columns based on properties that repeat from row to row Modern Periodic Table arranged by Henry Moseley Arranged by increasing atomic number

Parts of the Periodic Table ROWS Called Periods Go across COLUMNS Called Groups Go up and down Periods

7 periods Elements in the same period have: Same number of energy levels or shells or orbitals Groups 18 groups

Elements in the same group have the same: Properties Valence Electrons Oxidation Numbers Valence Electrons Number of electrons on the outermost (last)

energy level Code: 1, 2, 3, 4, 5, 6, 7, 8 Number next to A at the top of the column Know Your Roman Numerals

I=1 II = 2 III = 3

IV = 4 V=5 VI = 6 VII = 7 VIII = 8 Oxidation Number Number of electrons an atom will gain or lose to become stable

Stable = 8 electrons on last shell Code: +1, +2, +3, 4, -3, -2, -1, 0 + means lose electrons means gain electrons Labeling the Periodic Table

Bohrs Model Focuses On Electrons Places electrons into energy levels Developed by Neil Bohr Components of Bohrs Model Circles

Number of Circles = Period Number = Number of Energy Level DOTS Go on the Last Circle Number of Dots = Number

of Valence Electrons Important Note First energy level has a max of 2 electrons All other energy levels have a max of 8 electrons Steps to Draw Bohrs Model 1. Place a dot to be Nucleus

2. Place circles around Nucleus 3. Place dots on last circle in correct order EXAMPLE Oxygen Bohr Model Practice

NEON Boron Helium Electron Dot Diagrams Model of an atom in which each dot represents the

valence electrons AKA: Lewis Dot Diagrams Steps to Draw Dot Diagrams 1. Identify the number of valence electrons 2. Write the elements symbol 3. Place dots around the

symbol equal to valence electrons in correct order Example NEON Dot Diagram Practice Fluorine

Sodium Carbon Classifying Elements Elements are classified as metals, nonmetals, or metalloids based

on properties and location on the periodic table Metals Most elements are them Good Conductors of electricity/heat Solid at room temperature (except

Mercury) Ductile: turn into thin wire Luster: reflect light Malleable: hammer into sheets High Melting Point Left side of the stair step Francium: Most reactive

metal High Boiling Point Nonmetals Dull Brittle Poor Conductors of electricity/heat Most are gas at room temperature

Low Melting Point Low Boiling Point Right Side of Stair Step Fluorine: most reactive nonmetal Metalloids Have BOTH characteristics of metals and nonmetals

Found on the stair-step line What are the Metalloids B, Si, Ge, As, Sb, Te, Po, At Periodic Trend Reactivity As you go left to right across a

period, the less reactive elements become THE FAMILIES AND GROUPS OF THE PERIODIC TABLE Alkali Metals

Group IA 1 valence electron Reactivity increases from top to bottom Francium is most reactive metal Alkaline Earth Metals Group IIA

2 valence electrons Ca: is in your bones, teeth, shells Transitional Metals THE MIDDLE OF THE PERIODIC TABLE Groups 3B-12B Vary in oxidation numbers

Brightly colored Likes to combine with Oxygen BORON FAMILY Group IIIA 3 valence electrons Al: most abundant metal in Earths crust

Carbon Family Group IVA 4 valence electrons Carbon is the element of life Nitrogen Family Group VA 5 valence electrons

N is 78% of air Main component of fertilizer Oxygen Family Group VIA 6 valence electrons O: most abundant element in Earths crust

The Halogens Group VIIA 7 valence electrons

Salt formers Reactive with metals Fluorine: most reactive nonmetal Noble Gases Group VIIIA 8 valence electrons Stable = not reactive

Inert Gases All Shells are full

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