2 Pre-Periodic Table Chemistry … …was a mess!!!No organization of elements.Imagine going to a grocery store with no organization!!Difficult to find information.Chemistry didn’t make sense.
3 Dmitri Mendeleev: Father of the Table HOW HIS WORKED…Elements in rows (periods) by increasing atomic weight.Elements in columns (families) by the way they reacted.SOME PROBLEMS…Left blank spaces for what he said were undiscovered elements. (Turned out he was right!)Pattern of increasing atomic weight was broken to keep similar reacting elements together.
4 The Current Periodic Table Mendeleev wasn’t too far off.Now the elements are put in rows by increasing ATOMIC NUMBER!The horizontal rows are called periods and are labeled from 1 to 7.The vertical columns are called groups or families and are labeled from 1 to 18.
5 Groups…Here’s Where the Periodic Table Gets Useful!! Why?Elements in the same group have similar chemical and physical properties!!(Mendeleev did that on purpose.)They have the same number of valence electrons.They will form the same kinds of ions.
6 Groups/Families on the Periodic Table Columns are called groups or families.Groups may be one column, or several columns put together.Groups have names rather than numbers. (Just like your family has a common last name.)GROUP
7 Groups are also called families. They are vertical columns.
8 Periods Row on the period table Elements in the same period have the same number of electron ringsVery different properties as you move across the tableExamples:Period 1~ H and He 1 electron shellPeriod 2~ Li, Be, B, C, N, O, F, 2 electron shellsEtc……..
10 Hydrogen Belongs to a family of its own. Diatomic, reactive gas. Was involved in the explosion of the Hindenberg.Promising as an alternativefuel source for automobiles
11 Alkali Metals1st column on the periodic table (Group 1) not including hydrogen.Very reactive metalsAlways combined with something else in nature (like in salt).Soft enough to cut with a butter knife1 valence electron
12 Alkaline Earth Metals Second column on the periodic table. (Group 2) Reactive metalsAlways combined with nonmetals in nature.Several are important mineral nutrients (Mg and Ca)2 valence electrons
13 Transition Metals Elements in groups 3-12 Less reactive harder metals Includes metals used in jewelry and construction.Metals used “as metal.”
14 Boron Family Elements in group 13 Aluminum metal was once rare and expensive, not a “disposable metal.”3 valence electrons, +3 ions form
15 Carbon Family Elements in group 14 Contains elements important to life and computers.Carbon is the basis for an entire branch of chemistry.Silicon and Germanium are important semiconductors.
16 Nitrogen Family Elements in group 15 Nitrogen makes up over ¾ of Earth’s atmosphere.Nitrogen and phosphorus are both important in living things.Most of the world’s nitrogen is not available to living things.The red stuff on the tip of matches is phosphorus.
17 Oxygen Family Elements in group 16 Oxygen is necessary for respiration.Many things that stink, contain sulfur (rotten eggs, garlic, skunks,etc.)
18 Halogens Elements in group 17 Very reactive, volatile, diatomic, nonmetalsAlways found combined with other element in natureUsed as disinfectants and to strengthen teeth
20 The Noble Gases Elements in group 18 VERY unreactive (STABLE), monatomic gasesUsed in lighted “neon” signsUsed in blimps to fix the Hindenberg problem.Have a full valence shell.
21 Lanthanide SeriesOne of two rows that “sits off” to the bottom of the periodic tableReactiveFairly soft metals
22 Actinide Series Also towards bottom of periodic table All are radioactive, some are not found in natureSome with higher atomic numbers have only been made in labs
23 Periodic Trends Atomic Radius – related to the atom’s volume. Period – atomic radius decreases as you go from left to rightGroup – atomic radius increases as you go down a group
24 Periodic TrendsElectronegativity – the atoms “desire” to grab another atom’s electrons.Period – electronegativity increases as you go from left to rightGroup – electronegativity decreases as you go down a group
25 Periodic TrendsIonization Energy – amount of energy needed to remove the outermost electron. Closely related to electronegativity.What does this mean? Elements in the same group tend to form the same type of ion.Group 1: +1, group 2: +2, group 13: +3, Group 15: -3, group 16: -2, group 17: -1, group 18: do not form ions.
26 Periodic Trends Metals, Metalloids, Nonmetals Metals on the left – solid at room temp, shiny, hard, malleable, ductile, conducts electricity and heat well, most reactive groups are group 1 and 2.Metalloids at the break– properties vary, some metallic and some nonmetallic properties, soft, solid at room temp, conduct electricity poorly or under specific circumstancesNon-Metals on the right– many are gas at room temp, not malleable or ductile, poor conductors of electricity, most reactive groups are group 16, 17. Group 18 is INERT.
27 Periodic TrendsReactivity – how likely or how vigorously an atom is to react with another substance.Non-MetalsPeriod - reactivity increases as you go from left to rightGroup – reactivity decreases as you go down the groupMetalsPeriod – reactivity decreases as you go from left to rightGroup – reactivity increases as you go down a group