9/9/20151 Periodic Table The Basics Chemistry Mrs. Sousa & Mr. Pickin

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Periodic Table The Basics

Chemistry

Mrs. Sousa & Mr. Pickin

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Introduction

This presentation will give you all the information you need to know about the basic organization of the periodic table

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Origin

The periodic table was first devised by Dmitiri Mendeleev in Russia in 1869

Based on the “Periodic Law” which states that the properties of the elements repeat periodically

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Basics Elements listed by increasing atomic number

(Unique for each element) (thus properties)

Atomic number is the number of protons contained in the nucleus of an atom of an element

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Major Divisions in Table Metals (<4 valence electrons)

form + ions (cations). Ionic bonds Non-metals (>4 valence electrons)

form - ions (anions). Covalent bonds Metalloids (semi-metals) Separated by zig-zag line Image

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Periods

Horizontal (across) rows are called periods. Properties of elements change across the period.

7 periods (maximum)

Period number is the number of energy levels each element contains in that row(quantum # n value as well)

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Groups/FamiliesEither term acceptable

Vertical columns 18 families

Numbered from left to right

Members of the same family have very similar chemical and physical properties. Atoms increase in size as you get lower in a group.

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Representative Families. Representative families are 1,2,13,

14,15,16,17,18 Ones place is the number of valence electrons In other words- for 13-18 put your finger over the #1! Ex. Family 16 has 6 valence electrons Valence electrons are those in the outer energy level –

they are used for bonding and come from the s & p orbital space

Noble Gases (group #18) all have 8 valence electrons. Exception to the octet rule: He (helium) has 2 valence

electrons

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Common Names 1-Alkali metals (most active metals) 2-Alkaline earth metals 16-Chalcogens 17-Halogens (most active non-metals) 18- Noble gases (not reactive) 3-12 Transition metals (1 or 2 valence

electrons)

Lanthanide series (AN 57-71)

Actinide series (AN 89-103)

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Regions of the Periodic Regions of the Periodic TableTable

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Group 1: Alkali Group 1: Alkali MetalsMetalsGroup 1: Alkali Group 1: Alkali MetalsMetals

Cutting sodium metalCutting sodium metal

Reaction of potassium + H2O

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MagnesiumMagnesium

Magnesium Magnesium oxideoxide

Group 2: Alkaline Earth MetalsGroup 2: Alkaline Earth Metals

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Group 17: The Group 17: The Halogens (salt Halogens (salt makers) makers) F, Cl, Br, I, AtF, Cl, Br, I, At

Group 17: The Group 17: The Halogens (salt Halogens (salt makers) makers) F, Cl, Br, I, AtF, Cl, Br, I, At

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Group 18: Group 18: The Noble (Inert) The Noble (Inert) GasesGases

He, Ne, Ar, Kr, Xe, RnHe, Ne, Ar, Kr, Xe, Rn

Group 18: Group 18: The Noble (Inert) The Noble (Inert) GasesGases

He, Ne, Ar, Kr, Xe, RnHe, Ne, Ar, Kr, Xe, Rn

Lighter than air balloons

“Neon” signs Very Unreactive

because they have full electron levels

XeOFXeOF44XeOFXeOF44

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Transition Metals (elements) Families 3-12 Lanthanide series click Actinide series Multivalent – can have 1, 2, 3 valence

electrons – depending on what other atoms they are bonding with.

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Transition Transition ElementsElementsTransition Transition ElementsElements

Lanthanides and actinidesLanthanides and actinides

Iron in air gives Iron in air gives iron(III) oxideiron(III) oxide

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s, p, d, f blocks

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Atomic Radius (size) • The trend is that:

•Atoms get smaller going across a period (Noble gases are the exception)

•Atoms get larger going down a family

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Atomic Radius (cont.)

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Atomic Radius (cont)

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Ionization Energy (IE)

The amount of energy necessary to remove one or more electrons from an atom in its gaseous state

Generally: Metals have low IE Non-metals have high IE

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Ionization Energy (IE)

IE increases across a period IE decreases down a family

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Electronegativity (EN) The tendency of an atom to attract electrons (affinity for

electrons)

An atom's electronegativity is affected by both the positive charge in the nucleus and the distance that its valence electrons reside from the charged nucleus.

The higher the associated electronegativity number, the more an element or compound attracts electrons towards it.

Range of EN’s for the elements is 0.7 (Fr) to 4.0 (F) Trend:

EN increases across a period and decreases

down a family

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Electronegativity (EN) Trend

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Electronegativity (cont.)

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Electron Affinity The energy released when an electron is

added to a neutral atom. (exothermic process) for the first added electron the process is exothermic