Introduction to the Periodic Table Atomic Number ● Symbol ● Atomic Weight Element ● Compound
I am Dmitri Mendeleev! I made the PERIODIC TABLE !
What is the PERIODIC TABLE? • Shows all known elements in the universe. • Organizes the elements by chemical properties.
What is the ATOMIC NUMBER? • The number of protons found in the nucleus of an atom Or • The number of electrons surrounding the nucleus of an atom.
What is the SYMBOL? • An abbreviation of the element name.
What is the ATOMIC WEIGHT? • The number of protons and neutrons in the nucleus of an atom.
How do I find the number of protons, electrons, and neutrons in an element using the periodic table? • # of PROTONS= ATOMIC NUMBER • # of ELECTRONS= ATOMIC NUMBER • # of NEUTRONS= ATOMIC _ ATOMIC WEIGHT NUMBER
Now you are almost as smart as I am! But not as handsome! Man, I look GOOD!
What is an ELEMENT? • A substance composed of a single kind of atom. • Cannot be broken down into another substance by chemical or physical means.
What is a COMPOUND? • A substance in which two or more different elements are CHEMICALLY bonded together.
Why is the Periodic Table important to me? • The periodic table is the most useful tool to a chemist. • You get to use it on every test. • It organizes lots of information about all the known elements.
Pre-Periodic Table Chemistry … • …was a mess!!! • No organization of elements. • Imagine going to a grocery store with no organization!! • Difficult to find information. • Chemistry didn’t make sense.
HOW HIS WORKED… Put elements in rows by increasing atomic weight. Put elements in columns by the way they reacted. SOME PROBLEMS… He left blank spaces for what he said were undiscovered elements. (Turned out he was right!) He broke the pattern of increasing atomic weight to keep similar reacting elements together. Dmitri Mendeleev: Father of the Table
The Current Periodic Table • Mendeleev wasn’t too far off. • (Henry Mosley) Now the elements are put in rows by increasing ATOMIC NUMBER!! • The horizontal rows are called periods and are labeled from 1 to 7. • The vertical columns are called groups are labeled from 1 to 18.
A way of organizing & classifying elements • Arranged in rows and columns
Groups…Here’s Where the Periodic Table Gets Useful!! • Elements in the same group have similar chemical and physical properties!! • (Mendeleev did that on purpose.) Why?? • They have the same number of valence electrons. • They will form the same kinds of ions.
Families on the Periodic Table • Columns (groups)are also called families. • Families may be one column, or several columns put together. • Families have names rather than numbers. (Just like your family has a common last name.)
Columns • The vertical (up and down) columns of the periodic table (there are 18) are called groups or families. • Elements in the same group or family have similar characteristics or properties.
Rows • The horizontal rows of the periodic table are called periods. • Elements in a period are not alike in properties. • The first element in a period is usually an active solid, and the last element in a period is always an inactive gas.
Rows • Atomic number increases from left to right across a period. • Atomic mass (number of protons & neutrons) increases from left to right across a period.
Rows • Metals are on the left • Non-metals are on the right
Hydrogen • Hydrogen belongs to a family of its own. • Hydrogen is a diatomic, reactive gas. • Hydrogen was involved in the explosion of the Hindenberg. • Hydrogen is promising as an alternative fuel source for automobiles
ALKALI METALS • very reactive metals that do not occur freely in nature • softer than most other metals • Explode in water • Combine with Halogens to form salts • Valence electrons –1
ALKALINE EARTH METALS • metals • very reactive • not found free in nature • important mineral nutrients (such as Mg and Ca) • Valance electrons - 2
TRANSITION METALS • ductile and malleable, and conduct electricity and heat • iron, cobalt, and nickel, (Iron Triad) are the only elements known to produce a magnetic field.
Transition Metals • Elements in groups 3-12 • Less reactive harder metals • Includes metals used in jewelry and construction. • Metals used “as metal.”
RARE EARTH ELEMENTS • many are man-made • Lanthanides – soft metals that are very rare. Found in combination with Oxygen in the Earth’s Crust • Actinides – Radioactive, only 3 found naturals – others are man-made (Californium used to kill cancer cells)
OTHER METALS • are ductile and malleable • are solid, have a relatively high density, and are opaque
METALLOIDS • have properties of both metals and non-metals • some of the metalloids, such as silicon and germanium, are semi-conductors(carry an electrical charge). This property makes metalloids useful in computers and calculators
NON-METALS • not able to conduct electricity or heat very well • very brittle, and cannot be rolled into wires or pounded into sheets • exist in two of the three states of matter at room temperature: gases (such as oxygen) and solids (such as carbon). • have no metallic luster, and do not reflect light.
HALOGENS • "halogen" means "salt-former" and compounds containing halogens are called "salts" • exist in all three states of matter: • Solid- Iodine, Astatine • Liquid- Bromine • Gas- Fluorine, Chlorine • Valence Electrons - 7
Halogens • Elements in group 17 • Very reactive, volatile, diatomic, nonmetals • Always found combined with other element in nature . • Used as disinfectants and to strengthen teeth.
NOBLE GASES • do not form compounds easily VERY unreactive Full valence (electron) shell Used in lighted “neon” signs Used in blimps. Valence Electrons - 8