Elements and the Periodic Table

Periodic table The periodic table contains information on all the ELEMENTS in the world. An element is a PURE substance made of atoms. An atom is the SMALLEST thing in the world that an element can be broken down into.

Elements Pure substances that cannot be separated into different substances by ordinary processes Are the building blocks of matter 118 elements known today Examples: carbon gold calcium

Symbols of Elements Use 1 or 2 letter abbreviations Capitalize the first letter only Examples: C carbon Co cobalt N nitrogen Ca calcium F fluorine Br bromine O oxygen Mg magnesium LecturePLUS Timberlake

Symbols from Latin Names Element Symbol Latin name Copper Cu cuprum Gold Au aurum Lead Pb plumbum Mercury Hg hydrargyrum Potassium K kalium Silver Ag argentum Sodium Na natrium Tin Sn stannum LecturePLUS Timberlake

Learning Check Select the correct symbol for each: A. Calcium 1) C 2) Ca 3) CA B. Sulfur 1) S 2) Sl 3) Su C. Iron 1) Ir 2) FE 3) Fe LecturePLUS Timberlake

Solution Select the correct symbol for each: A. Calcium 2) Ca B. Sulfur 1) S C. Iron 3) Fe LecturePLUS Timberlake

Learning Check Select the correct name for each: A. N 1) neon 2) nitrogen 3) nickel B. P 1) potassium 2) phogiston 3) phosphorus C. Ag 1) silver 2) agean 3) gold LecturePLUS Timberlake

Solution Select the correct name for each: A. N 2) nitrogen B. P 3) phosphorus C. Ag 1) silver LecturePLUS Timberlake

The periodic table arranges the elements according to similarities in their chemical and physical properties.

Physical properties The characteristics of a substance that can be observed without changing the substance. Colour Size Lustre Shape Density Freezing and Boiling Points Smell

Chemical properties Number of valence electrons Reactivity Type of reactions typically made Response to water/ acid…

The Periodic table is organised into GROUPS and PERIODS

Groups The vertical columns are called groups (sometimes called families) Each group of elements has similar PHYSICAL AND CHEMICAL properties

Groups in the Periodic Table 1 2 3 4 5 6 7 8

The periodic table and electrons The location of an element on the periodic table is directly related to the number and arrangement of the electrons of that element

Valence Electrons The number of valence electrons in an atom may also be indicated. Valence electrons are the electrons in the outer energy level of an atom. These are the electrons that are transferred or shared when atoms bond together.

Reminders: Valence electrons – electrons in the outer energy level of an atom Mass number – number of protons plus neutrons in the nucleus of a particular kind of atom Atomic number – the number of protons in a particular kind of atom

Periods on the Periodic Table Horizontal rows from Group 1 to Group 8. Numbered 1, 2, 3, …. Include representative elements and transition elements

Periods on the Periodic Table 1 2 3 4 5 6

Periods

Groups versus periods Groups Periods Columns of elements Elements in each group have similar but not identical properties. For example,Group 1A: [ lithium (Li), sodium (Na), potassium (K), and other members of family IA] are all soft, white, shiny metals. All elements in a group have the same number of valence electrons. Horizontal row of elements The elements in a period do NOT have similar chemical or physical properties. Elements in same period have same number of energy levels (electrons) Properties change greatly across every period The first element in a period is always an extremely active solid. The last element in a period is always an inactive gas.

Periodic Trends Atomic mass increases as you move right and down Elements of a period are listed consecutively in order of increasing atomic number 3 4 5 6 7 8 9 10

Spotting characteristics 1: Metals versus non-metals

Metals

Properties of Metals Physical properties Metals are good conductors of heat and electricity. Metals are shiny. Metals are ductile (can be stretched into thin wires). Metals are malleable (can be pounded into thin sheets) Usually solid at room temperature (except mercury) A chemical property of metal is its reaction with water which results in corrosion.

Non-Metals

Non-Metals Located on the right side of the periodic table (except for Hydrogen) Usually found as a gas at room temperature Not malleable or ductile Do not conduct heat or electricity well The noble gases are the only group that contains ALL non-metals Sulphur

Metals versus non-metals

Metals and Nonmetals NONMETALS METALS METALS Transition metals LecturePLUS Timberlake

Physical Properties of NONMETALS Nonmetals are insulators. They do not conduct electricity or heat well. The atoms in non-metals do not have ‘loose’ electrons. When electricity or heat touches a non-metal, the energy does not move quickly through the material. What would you rather stir a hot pot with—a wooden spoon or a metal spoon?

Physical Properties of NONMETALS Nonmetals are soft and brittle (except for diamonds and graphite. Sulphur

An interesting element: Carbon Ever break the point of your pencil? That’s because it’s made of graphite, a substance made up completely of Carbon—a brittle nonmetal. Carbon atoms in graphite However diamonds, the hardest material of all, are made of the same element: Carbon. Look at how the carbon atoms are arranged in diamonds—why do you think diamonds are harder than graphite? You may also want to discuss how we are using carbon to create new materials such as nanotubes, or discuss buckeyballs.

Metalloids

The elements contained in the classification of Metalloids:

Metalloids (also called semi-metals) Can have both metallic and non-metallic properties Usually ductile and malleable Some metalloids conduct electricity better than non-metals but worse than metals – these are termed semiconductors

METALLOIDS Elements classified as Metalloids have physical properties of both metals and non-metals. Some are shiny, some are dull, they are somewhat malleable and ductile, and can conduct heat and electricity at a lesser level than metals. SILICON ARSENIC BORON

METALLOIDS Some metalloids are useful semiconductors, which are used in electronics (radio, computers, telephones, etc.) They are useful because they conduct just the right amount of electricity or heat.

More about metals The alkali metals The alkaline earth metals Do all metals behave the same?

Where do we find METALS? Some metals like gold, silver, and platinum are found as pure substances in the earth’s crust because they are least reactive. Most metals are reactive and are found as oxides (react with oxygen), carbonates (react with carbon), sulfides (react with sulfur). Minerals : are elements or compounds which occur naturally inside the earth’s crust. Ore : is a mineral from which metals can be extracted profitably.

Metals are not all equally reactive

Alkali Metals H Li Na K Rb Cs Fr

Alkali Metals Elements found in Group 1A Most reactive of all metals – SUPER-REACTIVE (so need to be stored in oil) Not found as mono-elements in nature – they need to be extracted from compounds Each alkali metal has one valence electron (which is EASY to lose…)

Testing reactivity… Drop it in water Heat it Drop it in acid Mix it with oxygen Displacement reactions…

Alkaline Earth Metals Be Mg Ca Sr Ba Ra

Alkaline Earth Metals Elements found in Group 2A Combine readily with other elements Have low electron affinities and electronegativities The radius is of the nucleus is smaller than that of group I metals Each alkaline earth metal has 2 valence electrons

Transition Metals

Transition elements Elements found in the middle block of the periodic table The elements occur often in nature as uncombined elements Similar properties, but not similar number of valence electrons. Iron is the most commonly used transition element and is the second most common element in the earth’s crust

Halogens F Cl Br I At

Halogens Elements found in Group 7A Very reactive elements Each halogen has 7 valence electrons

Noble Gases He Ne Ar Kr Xe Rn

Noble Gases Elements found in Group 8A Very stable because their outer energy level is full Each noble gas has 8 valence electrons

Lanthanide and Actinide Series Lanthanide Series Actinide Series

Bohr model relates to periodic table The first period on the table has two elements…and the first energy level holds two electrons. The second period has eight elements…and the second energy level holds eight electrons.

Bohr’s atomic model relates to periodic table The first period on the table has two elements…and the first energy level holds two electrons. The second period has eight elements…and the second energy level holds eight electrons. Period determines the number of energy levels. Group determines the number of electrons in the valence shell.

Bohr model of Carbon C p + = 6 n = 6 12-6

group 4 = 4 valence electrons Bohr Model of Carbon e - period 2 = 2 energy levels group 4 = 4 valence electrons e - p + = 6 e - e - n = 6 e - e -