Presentation on theme: "Elements and the Periodic Table"— Presentation transcript:
1 Elements and the Periodic Table A Brief History….
2 Ancient Names for the elements PlumbumNatriumAurumArgentumHydrargyrumKaliumFerrum
3 John Dalton - Atomic Theory Proposed in 1803:(1) all matter was composed of small indivisible particles termed atoms,(2) atoms of a given element possess unique characteristics and weight(3) three types of atoms exist: simple (elements), compound (simple molecules), and complex (complex molecules).
7 Jons Jacob Berzelius (1779-1848) Proposed using the first or a second letter for the element symbol.
8 Modern Element Symbols Each element has its own symbol.In writing a symbol, we use 1 or 2 letters.The first letter is always capitalized, the second is not.Some elements kept symbols for Latin or Greek words.Elements are grouped in the periodic table.
10 The Periodic TableThe periodic table is a system which helps to classify the elements.In 1735, there were only 13 known elements; in 1850, there were 47; today there are over 100, including several man-made elements.
11 The Periodic Table (continued) The periodic table we use today was devised by a Russian scientist named Dmitri Mendeleev in 1869.
21 Periodic Table Information A periodic table can tell us many things:Elements are arranged in order of atomic numbers (number of protons in the nucleus)Atomic weight or mass of an element (number of protons and neutrons)Metals and non-metals are separated in the upper right corner by a zigzag line.
24 Properties of metalsAll solids at room temperature, except mercury (liquid)ShinyMalleable (bendable)Good conductors of heat and/or electricityDuctile (can be drawn into thin long wires)Most react with acidsLocated left of the staircase line in the periodic table.
26 Properties of non-metals Most are gases, some are solids, bromine is the only liquid,DullBrittlePoor or nonconductorsDo not react with acidsLocated right of the staircase line in the periodic table.
27 Metalloids (semi-metals) Elements that have some properties of metals and some of nonmetals.Include all elements on either side of the staircase line except AL and At.Also includes one form of C, called graphite, which is dull and brittle (nonmetal) but is a good conductor of electricity (metal).
28 Periodic Table Information Horizontal rows are called periods.Vertical columns are called groups or families (all elements in the same group have similar characteristics).The group number is the number of electrons in the outside level or orbit of an atom. These are called valence electrons.The groups on the periodic table have different names:Group A – Representative elements (1,2,13-18)Group B – Transition elements (3-12)
29 Chemical Families (groups) Group 1 (IA) – alkali metalsGroup 2 (IIA) – alkaline earth metalsGroup 17 (VIIA) – halogensGroup 18 (VIIIA) – noble gasesRows on the bottom:Lanthanide seriesActinide series
32 Chemical Families – Alkali metals group 1, IAEg. Sodium, lithium- Show metallic properties- Highly reactive, especially with water; reactivity increases down the group- Cs and Fr are the most reactive metals.
33 Alkaline earth metals Group 2, IIA Eg. Calcium, magnesium - show metallic properties- less reactive than alkali metals; reactivity increases down the group
34 Halogens Group 17, VIIA Eg. Chlorine, fluorine - show nonmetallic properties- reactivity decreases going down the group; F is the most reactive nonmetal- react with metals to produce salts (ionic compounds)- react with hydrogen to form compounds that dissolve in water to form acids.
35 Noble Gases Group 18, VIIIA Helium, neon, argon - show nonmetallic properties- extremely low chemical reactivity