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 (letters) 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

 

 

 

 

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