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Periodic Table
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Element Names & Symbols
Shorthand Usually 1st letter of the name 1st letter capital, others lowercase 2nd & 3rd letters help identify elements that start with the same letters Some names are from the Latin words Named for scientists, places, or properties
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Atomic Structure Element - only one kind of atom
Atomic Structure Element - only one kind of atom Cannot be further broken down ex- Pb, Cu, Ne, He, H, O, C Periodic Table – all known elements naturally occurring Earth artificially made in labs not created (yet)
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Periodic Table 1834 – 1907 Russian chemist Mendeleev arranged all elements known by mass Found patterns Predicted mass & properties of undiscovered elements Problems? atomic #s didn’t match up when arranged by properties New table – atomic #s match up, Mosley
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Table Parts Period - horizontal row of the table
Family/Group vertical columns, have similar properties
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Li: solid, Cs: liquid, Ar: gas, Tc: synthetic
Periodic Table 1 e- missing to fill shell (Halogens) # protons Full outer shell (Noble Gases) 1 e- in outer shell (Alkali Metals) Li: solid, Cs: liquid, Ar: gas, Tc: synthetic
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• Columns: Similar Valence Structure
Electropositive elements: Readily give up electrons to become + ions. Electronegative elements: Readily acquire electrons to become - ions.
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ELECTRONEGATIVITY • Ranges from 0.7 to 4.0,
• Large values: tendency to acquire electrons. Smaller electronegativity Larger electronegativity
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Horizontal rows are called PERIODS
Mendeleev The periodic table arranges all the elements in groups according to their properties. Vertical columns are called GROUPS Horizontal rows are called PERIODS
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Fact 1: Elements in the same group have the same number of electrons in the outer shell (this correspond to their group number) H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Fe Ni Cu Zn Br Kr Ag I Xe Pt Au Hg These elements have __ electrons in their outer shells These elements have __ electrons in their outer shell E.g. all group 1 metals have __ electron in their outer shell 8 1 3
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Fact 2: As you move down through the periods an extra electron shell is added:
E.g. Lithium has 3 electron in the configuration 2,1 H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Fe Ni Cu Zn Br Kr Ag I Xe Pt Au Hg Sodium has 11 electrons in the configuration 2,8,1 Potassium has 19 electrons in the configuration __,__,__,_ 2 8 8 1
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Fact 3: Most of the elements are metals:
These elements are metals H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Fe Ni Cu Zn Br Kr Ag I Xe Pt Au Hg These elements are non-metals This line divides metals from non-metals
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E.g. consider the group 1 metals. They all: Are soft
Fact 4: (Most important) All of the elements in the same group have similar PROPERTIES. This is how I thought of the periodic table in the first place. This is called PERIODICITY. H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Fe Ni Cu Zn Br Kr Ag I Xe Pt Au Hg E.g. consider the group 1 metals. They all: Are soft Can be easily cut with a knife React with water
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Alkali Metals: Group 1 Extremely reactive: only found in nature combined in compounds Solids at room temp, conduct heat & electricity, soft, low m.p. low density, react with acids, malleable, ductile, luster, 1e- in outer energy level (+1 cation) Identified by flame test
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Group 1 – The alkali metals
Na K Rb Cs Fr
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Group 2 – Alkaline Earth Metals
Highly reactive, never found free in nature (except beryllium, Be) Low density React with acids 2e- in outer energy level (+2 cation) Identified by flame test
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Group 3 – 12: Transition Metals
Common metals, properties vary High m.p. - react with acids Brittle, soft, strong, hard, malleable, ductile Alloys – mixture of 2 or more metals to gain desired characteristics cations Ores – mineral or other natural material from which one or more metals can be obtained
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Transition Elements Bright colors of gemstones
Iron, cobalt & nickel = magnetic fields Copper, gold & silver = coins Mercury – room temp.
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Groups 13 – 17: Nonmetals Insulators for electricity, dull, brittle
Not reactive w/ acids Solids, liquids & gases React with metals to form compounds Group 17: Halogens Form salts, all 3 room temp Toxic, different colors Metalloids Properties of metal & nonmetals stairstep
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Nonmetals Diatomic 7 Less reactive further down the column
Halogens & Noble gases Sublimation – solids change into vapors - ex. Iodine
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Mixed Groups Semiconductors – conduct electric current under certain conditions Allotropes – different forms of the same element Graphite & diamonds = carbon O2 & O3 both are oxygen
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Buckminsterfullerene
Carbon • All organic compounds are composed of carbon • The “building block” of organic compounds. • Carbon can form allotropes. Allotropes - Different physical forms of the same element. Graphite Diamond Buckminsterfullerene “Bucky Ball”
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Oxygen molecule O2 O O Allotropes O Ozone = O3 O O
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Group 17 – Halogens 1) Reactivity DECREASES as you go down the group
(This is because the electrons are further away from the nucleus and so any extra electrons aren’t attracted as much). Cl Cl 2) They exist as diatomic molecules (so that they both have a full outer shell): 3) Because of this F and Cl are liquid at room temperature and bromine is a gas
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Uses of Halogens F – kills harmful bacteria in water supplies & keeps teeth healthy. Cl: used in swimming pools Br: in pesticides AgBr used in photography I: antiseptic on cuts etc. Name derived from the Greek words hal, meaning “salt”, and genes, meaning “forming” React violently with alkali metals to form salts.
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1) Halogen + metal: Na + Cl - Na Cl + Halogen + metal ionic salt 2) Halogen + non-metal: Cl Cl H H + Halogen + non-metal covalent molecule
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Group 18 (8A): Noble Gases Perfect elements 8 valence electrons Inert- not reactive Helium (He) is the most abundant element in the universe.
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Group 18 – Noble Gases 1) All of the noble gases have a full outer shell, so they are very __________ 2) They all have low melting and boiling points 3) They exist as single atoms rather then diatomic molecules Helium is lighter then air and is used in balloons and airships Argon is used in light bulbs (because it is so unreactive) and argon , krypton and neon are used in fancy lights
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Hydrogen Smallest element Unique properties –
alkali metals or halogen?
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7 elements that exist as 2 atoms combined together in nature
Diatomic Seven 7 elements that exist as 2 atoms combined together in nature Hydrogen Nitrogen Oxygen Fluorine Chlorine Bromine Iodine Diatomic 7
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Synthetic Elements Made by combining existing elements w/ fast moving particles More than 92 protons = transuranium Unstable breakdown quickly
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Radioactive Elements Nucleus breaks down giving off particles & energy
Becomes other elements as the number of protons change
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Metallic Bonding
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