Atomic Structure and the History of the Atom

HISTORY Aristotle - One of the most influential Greek philosophers, whose theories were wrong most of the time. He strongly opposed the idea of the atom. He believed particles could be infinitely divided. Click here for biography on Aristotle

HISTORY 2 Democritus – A Greek philosopher, and student of Aristotle. He believed that things could be divided until the division reached a single particle that matter was composed of, then the splitting would stop when it reached indivisible particles and wouldn’t go on infinitely (forever).  Believed that atoms could not be created, destroyed, or further divided Click here for biography on Democritis

History 3 Dalton – An English chemist who is considered the father of the modern atomic theory. He believed that all elements are composed of atoms that cannot be created, destroyed, or further divided. Click here for biography on Dalton

History 4 Mendeleev – A Russian chemist, developed a periodic table of elements. He realized that the chemical and physical properties of the elements repeat in an orderly way when elements are organized according to increasing atomic mass. Click here for biography on Mendeleev

HISTORY5 Science has come a long way since Dalton, which has made it necessary to update his atomic theory. Current belief is that all elements are composed of atoms, but we know that those atoms are not indestructible. Atoms can be split (chemically) in nuclear reactions, and they are made up of even smaller particles called quarks! Click here for biography on QUARKS

Period # and Group # INFO Period # This number tells you how many rings to draw in the Bohr’s model of each of the elements. Group # This number tells you how many electrons can be found in the last ring of the Bohr’s model.

Atom Vs. Ion  Exactly the same except for the number of electrons  Protons and neutrons NEVER CHANGE  Use the Bond # song which matches the negative or positive number at the at the top of each column to determine the ionic charge  ANION = Negative ION  CATION= Postive ION

Bonding SONG  1bond, 2 bond, 3 bond, 4, 3 bond, 2 bond, 1 no more

ISOTOPES We also know that atoms of the same element can have different masses, when they represent different isotopes of that element. 1. Examples – Hydrogen has three isotopes a. Protium – 1 proton, 0 neutrons, 1 electron b. Deuterium – 1 proton, 1 neutron, 1 electron c. Trituim – 1 proton, 2 neutrons, 1 electron. Isotope VIDEO

How do we use Isotopes?? Click here for the video

What is Carbon Dating??? Click on the picture to watch a video about carbon dating….

Periods VS. Groups Can you draw the appropriate structure of each atom based on their location within the group? Watch the video and learn how!!

There are 2 group numbers…1 is the general group going across the table and the other is the Valence group number for 8 groups

Equals the number of shells located on the outside of the nucleus where the electron orbitals are found

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.

Families/groups on the Periodic Table Columns are also grouped into 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.)

Organization of Periodic Table Rows are called periods. Columns are called families or groups. All elements in a family have similar properties.

METALS

NON-METALS

Metalloids

ALKALAI METALS

Aklaline earth metals

Lathanides Actinides

BORON Family

Carbon Family

Nitrogen Family

Oxygen Family

HALOGENS

NOBLE GASES

Families on the Periodic Table Columns are also grouped into 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.)

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 first column on the periodic table. (Group 1) VERY Reactive metals. Extremely malleable Will cause an explosive reaction when placed within water

Alkaline Earth Metals Second column on the periodic table. (Group 2) Reactive metals that are always combined with nonmetals in nature. Several of these elements are important mineral nutrients (such as Mg and Ca

GROUPS OF ELEMENTS IN PERIODIC TABLE METALS Vast majority of elements are metals. Elements found to the left of the heavy black line on periodic table. Physical Properties: Appearance – high luster Tapping – malleable Conductivity – conductor of heat and electricity

Transition Metals Elements in groups Less reactive harder metals Includes metals used in jewelry and construction. Metals used “as metal.”

Carbon Family Elements in group 14 Contains elements important to life and computers. Carbon is the basis for an entire branch of chemistry. Silicon and Germanium are important semiconductors.

Nitrogen Family Elements in group 15 Nitrogen makes up over ¾ of the atmosphere. Nitrogen and phosphorus are both important in living things. Most of the world’s nitrogen is not available to living things. The red stuff on the tip of matches is phosphorus.

Oxygen Family or Chalcogens Elements in group 16 Oxygen is necessary for respiration. Many things that stink, contain sulfur (rotten eggs, garlic, skunks,etc.)

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.

GROUPS OF ELEMENTS IN PERIODIC TABLE NONMETALS Second most amount of elements. Elements found to the right of the heavy black line on periodic table. Properties that most nonmetals exhibit:  soft, does not conduct electricity and does not have a luster

GROUPS OF ELEMENTS IN PERIODIC TABLE METALLOIDS Elements that straddle the heavy black line Combination of metallic and nonmetallic properties.

GROUPS OF ELEMENTS IN PERIODIC TABLE NOBLE GASES Elements found in group 18. Extremely unreactive elements.

The Noble Gases Elements in group 18 VERY unreactive, monatomic gases Used in lighted “neon” signs Used in blimps to fix the Hindenberg problem. Have a full valence shell.

Reading the Periodic Table of Elements  PLEASE TAKE OUT YOUR PERIODIC TABLE  The largest number (with decimal) is the Atomic Mass # and is the weight of the atom and how many (+) and (n) are in the nucleus  The smaller number (no decimal) is the Atomic # and is the number of (+) or (-). REMEMBER the number of (+) and (-) should always be equal.  The Symbol represents the Latin name of the chemical and is used within equations.  Please memorize the ELEMENTS that were given to you!

PRACTICE, PRACTICE, PRACTICE Answer the following questions about Calcium: # of (-) # of (+) # of (n) Atomic # Atomic Mass # Symbol

ANSWERS Answer the following questions about Calcium: # of (-) 20 # of (+)20 # of (n)20 Atomic #20 Atomic Mass #40.06 SymbolCa

LET’S DO IT AGAIN… Answer the following questions about Aluminum: # of (-) # of (+) # of (n) Atomic # Atomic Mass # Symbol

ANSWERS Answer the following questions about Aluminum: # of (-)13 # of (+)13 # of (n)14 Atomic #13 Atomic Mass #26.98… SymbolAl

Atomic Structure Protons, neutrons and electrons are known as (subatomic particles)  All of the mass of an atom is found in the nucleus  Particles in the nucleus are called nucleons

Atomic Structure Continued  Two types of nucleons A. Protons – discovered by Rutherford  1. Positively charged (+) particles  2. number of protons = atomic number of element  3. The number of protons in an atom determines the type of element it will be.

Atomic Structure Continued B. Neutrons – discovered by Chadwick  1. neutral particle (no charge)  2. amount of neutrons in an element = take the atomic mass and subtract the atomic number

Atomic Structure cont… C. Electrons – discovered by JJ Thomson  1. Negatively charged (-) particle  2. Outside of the nucleus  3. Electrons found in a cloud around the nucleus  4. The electron cloud is called an orbital or shell

EXAMPLES OF TABLES Remember that every author has a different way of recognizing the families and placing the numbers regarding each of the elements in a different location. Learn how to read every periodic table

Select an element = Internet link ()