From Chemistry Today 1 3 rd ed Introducing the Elements

Discovering the Elements Earliest source of chemical energy was fire Approx 8000 years ago shiny materials appeared after heating rocks in fires-> soft metals such as copper, silver, gold These three easily hammered into shapes for tools, weapons jewelry Lead, tin, iron, mercury, carbon sulfur discovered around the same time

Discovering the Elements About 5000 years ago, some tin was added to melted copper and the new substance, bronze, was much tougher (for tools weapons). Bronze Age began. Greek philosophers saw ordinary materials placed in foundries in Alexandria, Egypt and large amounts of gold and silver coming out. They thought the Egyptian craftsmen were turning ordinary substances into gold! OMG ! The search began for the “philosopher’s stone” The researchers were known as alchemists ( al from Arabic meaning “the” and chymeia from Greek meaning “pouring” as in molten metals

Discovering the Elements By middle of 18 th century, phosphorus, zinc, arsenic, antimony and bismuth were discovered After electricity was discovered, currents were passed through compounds leading to discovery of sodium and potassium (1807) In 1808, boron, magnesium, calcium, strontium, and barium were also discovered. Now we have 90 naturally occurring elements of the 116 known

The periodic table Elements have been divided into metals, nonmetals and metalloids Metals ( from Greek metallon meaning “mine” are generally hard, shiny, good conductors of heat and electricity, malleable & ductile, and have high densities and boiling points e.g. gold, silver, aluminum. Nonmetals are generally poor conductors of heat and electricity, are not shiny or hard e.g. iodine, phosphorus, carbon (all solid), oxygen, nitrogen, chlorine (gaseous). Metalloids have some properties of both metals and non metals e.g. boron, silicon, germanium, arsenic, antimony, tellurium, polonium.The staircase or solid zigzag line separates the metals from nonmetals. Many of the elements bordering this line are metalloids.

What’s your element score? 1. Metal present in green pigments in plants used in photosynthesis. 2. Most important metal in mortal, plaster, & Portland cement. 3. Colourless, odourless gas used in hospitals to assist breathing. 4. The element used in yellow coloured light from highway lamps. 5. The element used in party balloons which some inhale to sound like Mickey Mouse.

Latin Names for Elements Chemical SymbolElement NameLatin Name NaSodiumnatrium CuCoppercuprum SnTinstannum AuGoldaurum PbLeadplumbum KPotassiumkalium AgSilverargentum SbAntimonystibium HgMercuryhydrargyrum FeIronferrum

The Periodic Table Around 1869 Dimitri Mendeleev, a Russian chemist, and Lothar Meyer, a German chemist discovered that if the known elements were listed in order of increasing atomic mass, elements with similar chemical & physical properties appeared at regular intervals in the list The modern periodic law states that when the elements are arranged in order of increasing atomic number, elements with similar properties occur at regular intervals. In other words, the physical and chemical properties of the elements are a periodic function of their atomic numbers

The Periodic Table

Horizontal rows are periods (numbered 1-7) correspond to shells or energy levels for the electrons Vertical columns are groups (numbered 1-18). Groups 1 & 2 have 1 and 2 valence (outer shell)electrons respectively. Groups have 3 to 8 valence electrons (i.e. Group # - 10). Note Group 18 has 8 valence electrons- a complete octet. Groups 3 to 12 are the transition metals Periods 6 & 7, have been compressed- i.e. the lanthanides (rare earth elements) & actinides have been placed below and aligned with groups 3 to 16