Periodic Table Scans

 

 

 

Periodic Table

 

Parts of an atom---

1.      nucleus---is a positively-charged body at the center of an atom (has protons and neutrons)

2.      protons—positive charged particles in the nucleus

3.      neutrons—neutral particles in the nucleus

4.      electrons—small negatively-charged particles that travel in an electron cloud that surrounds the nucleus

 

Two Diagram Examples:

           

 

Reading the Periodic Table---

  1. An element is matter made of atoms of only one kind.
  2.  chemical symbol (or symbol)--- the abbreviation of a chemical element; 1 to 3 letters; generally assigned in relation to its Latin name; 1st letter is capitalized; the other letter(s) are lower case
  3.  atomic number---the number of protons in the nucleus
  4. mass number (or atomic mass number)---the mass of the atom which is the number of protons plus neutrons      

                                                                       

  

 

5.      period or  row---going across the table; they are labeled 1-7; top to bottom of the table

6.      group or families---18 columns; each family contains elements that have similar physical or chemical properties

7.      representative elements---Groups 1, 2, and 13-18

8.      transition elements---Groups 3-12;  ALL metals

9.      inner transition elements---placed below the table; lanthanide and actinide series

 

Mendeleev created the first periodic table by arranging elements in order of increasing atomic mass. 

Groups on the table have similar properties.

 

 Types of Elements—

1.      metals:

s         hard, shiny, solids

s         luster---reflects light well

s         good conductors of heat and electricity

s         give up electrons easily

s         most are solid at room temperature

s         malleable: hammered, pounded, or rolled into sheets

s         ductile: drawn or stretched into wires

A.     Group 1: Alkali Metals---(not hydrogen)

s           most highly reactive of all metals

o       reactivity increases with increasing atomic number

o       reactivity---how likely an element is to form bonds with other elements

s         combines readily with other elements to form compounds

s         found in nature only in compounds

s         low densities; low melting points

s         give distinctive colors to flames

s           Uses: table salt, lithium batteries, treat bipolar disorder

                  B.     Group 2: Alkaline Earth Metals---

s           denser; harder; higher melting points

s           slightly less reactive and harder than group 1 metals

s           reactivity increases with increasing atomic number

s         Uses: chlorophyll is a magnesium compound that enables plants to make food

 2.   Groups 3-12: Transition Elements---

s         often form colored ions

o       An ion is an atom that has a positive or negative charge and form when atoms gain or lose electrons.

s         Some can be used as catalysts (speed up reactions)—platinum group, nickel, zinc, cobalt—to produce electronic and consumer goods, plastics, and medicines

s         Iron triad: iron, cobalt, nickel; only elements known to create a magnetic field

s         Iron is the main component of steel; most widely used of all metals; found in the hemoglobin of blood

s          Nickel is used to give other metals strength.

s         Coinage metals: gold, silver, copper

s          Copper used in electrical wiring

s         Mercury: liquid at room temperature; poisonous; once used in thermometers

    3.  Inner Transition Elements (placed below the table; rows 6-7)

s         Lanthanides: follows the element lanthanum

o       soft metals; can be cut with a knife; once thought to be rare

o       usually found combined with oxygen in Earth’s crust

s         Actinides: follows the element actinium

o       all are radioactive; several are synthetic (made in the lab) that do not occur naturally

o       the nucleus is unstable and decays to form other elements

       4.  nonmetals---

s        Usually gases or brittle solids at room temperature

s         Poor conductors of heat and electricity

s         Reactivity in nonmetals  increases as atomic number decreases---fluorine is the most reactive nonmetal

s         Dull; not malleable; not ductile

s         Many are essential to life: carbon, sulfur, nitrogen, oxygen, phosphorus, iodine

s         Carbon: essential for life; Carbon-14 Dating fossils to discover the age; diamonds and graphite (pencil lead) are made of carbon

s         Located on the right side of the table; except hydrogen

s            Bromine is the only nonmetal liquid at room temperature

s           Group 18: noble gases (once called inert)—

o       stable because outer energy level is full

o       least reactive elements; rarely combine

o       1962---scientists produced a compound of xenon and fluorine

o       Scientists have produced different substances that include every noble gas except helium. These substances form only under extreme conditions.

s           Group 17: halogens—

o       React with alkali metals to form salts (when a halogen gains an electron from a metal)

o       most abundant halogen is chlorine found in seawater

o       most reactive nonmetals

      5.  metalloids---

s           Properties of both metals and nonmetals

s           Many metalloids are semiconductors (partial conductors) of electricity

s         located along the stair-step line on the table

s         silicon: found in sand and in almost all rocks and soil

s           sulfur: creates paint pigments

 

Bohr Models---

1st shell can hold a maximum of 2 electrons; 2nd shell can hold up to a maximum of 8 electrons; 3rd shell can hold up to a maximum of 18 electrons

Lewis Structure (electron dot diagram)---represents the number of valence electrons in the outer most shell