Atoms and Elements: Are they Related? Fall 2011

ATOMS ALL MATTER IS MADE OF ATOMS Definition: ATOMS ARE THE SMALLEST PIECE OF MATTER and CANNOT BE BROKEN DOWN INTO A SIMPLER SUBSTANCE.

ATOMS HAVE 3 BASIC PARTS (Subatomic Particles) PROTONS NEUTRONS ELECTRONS

PROTONS (POSITIVE CHARGE) ARE FOUND IN THE NUCLEUS AND MAKE UP MOST OF THE MASS OF THE ATOM. VERY IMPORTANT!!! The number of protons an atom has tells you what kind of atom it is!!!!

The Atomic Number is the number of Protons Pg. 158

NEUTRONS (NO CHARGE) ARE FOUND IN THE NUCLEUS MAKE UP PART OF THE MASS OF THE ATOM

Finding the Number of Neutrons for an Atom The protons and neutrons make up the mass of an atom. If you know the protons (atomic number) then you can find the number of neutrons by subtracting the atomic mass from the # of protons (atomic number). atomic mass - # of protons = # of neutrons

Isotopes Atoms of the same element that have a different number of neutrons. EX: Carbon Carbon-12 Carbon-13 Carbon-14

Isotopes & Radioactive Decay Atoms are most stable when they have the same number of Pro/Neu in the nucleus… So, having more neutrons causes atom to be unstable & “repulsion” builds up. Nucleus becomes more stable when the extra particles are released & energy is given off. RD is the release of extra nuclear particles & energy.

ELECTRONS (NEGATIVE CHARGE - ) FOUND IN THE ELECTRON SHELL (cloud) ORBITING THE NUCLEUS. TAKES UP MOST OF THE SPACE IN AN ATOM. The # of electrons = the # of protons

Valence Electrons Outermost electron(s) in the cloud/shell 8 is the magic number!!!!!! (octet rule)

Ions Atom where the total number of electrons does not equal the total number of protons (atom will have a pos or neg charge) Cation= pos (loss of e-) Anion=neg (gain of e-) EX: Fe2+, Al3+, O2-

Label the atom below on your packet! What type of atom is this? How do you know?

Let’s Break for Questions??? How many protons should Hydrogen have? How about Oxygen? Which particles are located in the nucleus of an atom? Where are the electrons located?

Atomic Size -A typical atom is about one ten-billionth of a meter in diameter. (THAT’S REALLY, REALLY SMALL AND WHY WE CAN’T SEE THEM WITH A REGULAR MICROSCOPE) -ATOMIC MASS = Protons + Neutrons. -Most of the atomic mass comes from the nucleus. -Electrons weigh very little. That is why they do not add to the mass of the atom. -They DO contribute to the SIZE.

Isotopes & Mass Number So if protons and neutrons contribute to mass, if we have a different number of neutrons, will the mass be affected? EX: since C-14 has 8 neutrons, the mass number is 14amu instead of 12amu (C-12).

Discovery of the Atom (pg. 80) By the early 1800’s, John Dalton proposed that all substances are made up of atoms. In 1898, J.J. Thomson, proposed that atoms are made up of smaller parts. In 1911, Ernest Rutherford, proposed that atoms have electrons and a positively charged nucleus.

Dalton’s Atomic Theory All matter is made of atoms. Atoms are indivisible and indestructible. 2) All atoms of a given element are identical in mass and properties 3) Compounds are formed by a combination of two or more different kinds of atoms. 4) A chemical reaction is a rearrangement of atoms.

Niels Bohr’s model of the atom Electrons revolved around the nucleus in circular paths called orbits.

Electron Cloud Model Current Atomic Theory: Electrons travel in regions of various thicknesses called clouds.

ELEMENTS DEFINITION: PURE SUBSTANCES MADE OF ONLY 1 KIND OF ATOM. ARE THE BUILDING BLOCKS OF MATTER. CANNOT BE BROKEN DOWN INTO A SIMPLER SUBSTANCE. HAVE THEIR OWN UNIQUE SET OF PROPERTIES THAT NO OTHER ELEMENT HAS.

ELEMENTS There are 92 naturally occurring elements on the periodic table. This means they are in nature and not made in a laboratory by scientists. As of this year (2011) there are 118 confirmed elements. There are 4 more under investigation and scientific testing.

Let’s Stop for Questions! What type of atoms make up the element Lithium? Carbon? Sodium?

ELEMENTS ARE MADE OF ONLY 1 KIND OF ATOM. SOME COMMON ELEMENTS HYDROGEN (H), HELIUM (He), OXYGEN (0), Notice that the first letter is capital and the next letter is lower case.

Atoms and Elements Activity As a group, look at the food labels on the items at your table. Make a list of the items in the left hand side column and in the right hand side column make a list of any elements found in that substance. You may use your periodic table to help you identify the elements.

The food item would be: Cooked Ham What are the elements that are found on this food label?

QUESTIONS???? What are the most commonly occurring elements in the food labels? What items seemed to have the most amount of elements in them? Can you predict what that means about the food item? Why do you think the baby formula has such a variety of elements? Can you predict what the other items on the food label are if they are not elements?

Wrap Up Use your dry erase boards to write answers and hold them high!!! Protons have what charge? Electrons have what charge? Which parts of an atom make up the mass of the atom? Elements are made up of? The element lead is made up of what kind of atoms?

Periodic Table The periodic table is an organized table of each element. Each box gives information about each type of element found on Earth.

Dmitri Mendeleev (1869) In 1869 Mendeleev and Lothar Meyer (Germany) published nearly identical classification schemes for elements known to date. The periodic table is base on the similarity of properties and reactivities exhibited by certain elements. Later, Henri Moseley ( England,1887-1915) established that each elements has a unique atomic number, which is how the current periodic table is organized. http://www.chem.msu.su/eng/misc/mendeleev/welcome.html

ELEMENTS ARE ORGANIZED IN THE PERIODIC TABLE ACCORDING TO ATOMIC NUMBER.

ELEMENTS ARE ORGANIZED IN THE PERIODIC TABLE OF ELEMENTS ACCORDING TO THEIR SIMILAR CHARACTERISTICS 3 major groups: metals, nonmetals and metalloids See pg. 57 in book

Element Info in Each Box Atomic weight Atomic Number Symbol Name

Atomic Number- Number of Protons in an atom Silver = 47 protons Information from the periodic table Atomic Number- Number of Protons in an atom Silver = 47 protons

Elements & their symbols Iron- Fe (Ferrum) Lead- Pb (Plumbum) Elements & their symbols SOME COMMON ELEMENTS HYDROGEN (H), HELIUM (He), OXYGEN (0), Notice that the first letter is capital and the next letter is lower case. Gold- Au (Aurum)

Arrangement of the Periodic table Periods – Rows are called periods. The elements in these rows change conductivity and number of electrons as you move across the table. Groups – Columns are called groups or families. These elements have the same properties because of the number of electrons.

How is the Periodic Table Organized? Periods Even though they skip some squares in between, all of the rows go left to right. When you look at a periodic table, each of the rows is considered to be a different period

Across the Periodic Table Periods: Are arranged horizontally across the periodic table (rows 1-7) These elements have the same number of valence shells. 2nd Period 6th Period

When a column goes from top to bottom, it's called a group or family. Groups Groups are often called families because these elements seem to be related. **Elements in the same group show similarities in their chemical and physical properties.

Down the Periodic Table Family: Are arranged vertically down the periodic table (columns or group, 1- 18 or 1-8 A,B) These elements have the same number electrons in the outer most shells, the valence shell. Alkali Family: 1 e- in the valence shell Halogen Family: 7 e- in the valence shell

Reading the Periodic Table: Classification Nonmetals, Metals, Metalloids, Noble gases

Infamous Families of the Periodic Table Notable families of the Periodic Table and some important members: Alkali Alkaline (earth) Transition Metals Noble Gas Halogen Chalcogens

Alkali Group -Group #1 -1 valence electron in outer shell -very reactive with water & other elements -low densities & melting points

Alkaline Earth Group -Group #2 -2 valence electrons in outer shell -very reactive but not as much as alkali -denser, harder & higher melting points

Transition Metals -Groups 3-12 -Valence electrons vary -Usually found combined with other elements -higher melting points, good conductors

Halogen Group -Group #17 -7 valence electrons in outer shell -most combined to make salts (salt formers) -most are non-metals

Noble Gas Group -Group # 18 -8 valence electrons in outer shell (the happy gases! ) -NOT REACTIVE

Periodic Table: Metallic arrangement Layout of the Periodic Table: Metals vs. nonmetals Nonmetals Metals

Summary Periodic Table: Map of the Building block of matter Type: Metal, metalloid and Nonmetal Groupings: Representative or main, transition and Lanthanide/Actanides Family: Elements in the same column have similar chemical property because of similar valence electrons Alkali, Alkaline, halogens, noble gases Period: Elements in the same row have valence electrons in the same shell.

Elements are classified: *Metals *Nonmetals *Metalloids The Periodic Table Of Elements Elements are classified: *Metals *Nonmetals *Metalloids Xenon Scandium

Properties of a metal *Malleable - flattened *Good conductors – conducts heat or electricity *Malleable - flattened *Ductile – can be made into wires *Shiny- you can see you reflection Gold Iron Magnesium

Properties of a Nonmetal *Not malleable – cannot be flattened *Not shiny *Poor conductors Chlorine Helium Bromine

Silicon Arsenic Properties of Metalloids Semiconductors – Average conductors Shiny but brittle Silicon Arsenic Boron

Sulfur GOLD (AU) Silver

ELEMENTS IN OUR BODIES IODINE

1.Oxygen (65%) 2.Carbon (18%) 3.Hydrogen (10%) 4.Nitrogen (3%) 5.Calcium (1.5%) 6.Phosphorus (1.0%) 7.Potassium (0.35%) 8.Sulfur (0.25%) 9.Sodium (0.15%) 10.Magnesium (0.05%) 11.Copper, Zinc, Selenium, Molybdenum, Fluorine, Chlorine, Iodine, Manganese, Cobalt, Iron (0.70%) 12.Lithium, Strontium, Aluminum, Silicon, Lead, Vanadium, Arsenic, Bromine (trace amounts) 99% of the mass of the human body is made up of only six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. Every organic molecule contains carbon. Since 65-90% of each body cell consists of water (by weight), it isn't surprising that oxygen and hydrogen are major components of the body

Elements in the body Oxygen Carbon Hydrogen Nitrogen Calcium Phosphorus Potassium Sodium Chlorine Magnesium Sulfur

GASES FLUORINE KRYPTON NITROGEN NEON

Atoms to Elements to ???

ELEMENTS & COMPOUNDS ARE THE BASIC BUILDING BLOCKS OF MATTER EACH ELEMENT & COMPOUND HAS SPECIFIC PROPERTIES

COMPOUNDS ARE MADE OF 2 OR MORE DIFFERENT KINDS OF ATOMS/Elements BONDED TOGETHER

COMPOUNDS ARE MADE OF 2 OR MORE DIFFERENT KINDS OF ATOMS BONDED TOGETHER

Compounds http://web.neo.edu/rjones/Pages/1014new/Lecture/chemistry/chapter_9/pages/chemical_bonds.html

COMPOUNDS ARE MADE OF 2 OR MORE DIFFERENT KINDS OF ATOMS BONDED TOGETHER FOR A COMPOUND TO FORM, A CHEMICAL CHANGE MUST TAKE PLACE (A REACTION) THE ELEMENTS THAT COMBINE MAKE A NEW SUBSTANCE WITH NEW PHYSICAL PROPERTIES COMPOUNDS CANNOT BE BROKEN DOWN PHYSICALLY. REQUIRES A CHEMICAL CHANGE MORE COMMON THAN ELEMENTS NaCl TABLE SALT + =

+ = COMPOUNDS ARE IDENTIFIED BY A CHEMICAL FORMULA THE ELEMENTS THAT COMBINE TO MAKE THE COMPOUND CHANGE PROPERTIES NaCl TABLE SALT + =

Atomic Structure & Chemical Bonds Octet rule= when atoms of elements react, they ten to lose, gain or share electrons to achieve the same electron arrangement as the noble gases.

3 Ways Elements Bond Ionic= loss or gain of electron (metal + non-metal) Metallic= metal atoms share pooled electrons (pooling=electrons gathered together) Covalent=sharing of electrons (non-metal elements)

Ionic

Covalent Carbon forms lots of covalent bonds

Metallic

A way of writing how many atoms are in a compound.

Chemical Formulas Written as: C4H10 Butane Written as: CH4 Methane

Subscripts= how many atoms = how many total molecules Subscripts= how many atoms

FeO2 H2O C6H12O6 2Li + 2O2

Chemical Changes Through Chemical Reactions A chemical reaction – Process in which the physical and chemical properties of the original substance(s) CHANGE as new substances with different properties are formed.

A burning match is a good example of a chemical reaction. Application of a spark to the chemicals on the match head start the chemical reaction. Signs of a chemical change – heat given off, light given off, new substance formed – black material on the match head when the fire is extinguished.

Parts of a Chemical Reaction REACTANTS CHANGE INTO PRODUCTS Reactants – Substances that begins the chemical reaction (chemicals on match head) Products – Substances produced in the reaction (black material on match) In other words: REACTANTS CHANGE INTO PRODUCTS

takes the place of an = sign Shows substances combine CHEMICAL EQUATIONS Chemical equations are symbols used to describe the details of a chemical reaction. Shows how the reactants changed into the product. This involves indicating all the atoms involved in the reaction. Fe + O2 FeO2 Arrow: Means “yields” takes the place of an = sign Reactants: Iron and oxygen Product: Ferrous oxide (rust) Plus Sign: Shows substances combine

Law of Conservation of Matter Matter cannot be created or destroyed, it just changes forms. The total mass of the reactants must equal the total mass of the product.

Law of Conservation of Mass Alka-Seltzer and Water http://www.sky-web.net/science/balancing_chemical_equations_examples.htm

Balancing Equations The number of atoms of the reactants must equal the number of atoms in the product. (Law of Conservation of Matter) Ex: 2Na + Cl2 -> 2NaCl 4P + 5O2 -> P4O10

Balancing Equations Rules Make sure that all atoms are equal on both sides. You can only add coefficients. Changing the subscripts will change the identity of the compound. H2O & H2O2 EX: 2Na + Cl2 -> 2NaCl H2 + O2 -> 2H2O (Not balanced… So…) 2H2 + O2 -> 2H2O

Hg + O2 HgO H2 + Cl HCl Mg + O2 MgO O2 + H2 H2O CH4 + O2 CO2 + H2O Balancing Chemical Equations Hg + O2 HgO H2 + Cl HCl Mg + O2 MgO O2 + H2 H2O CH4 + O2 CO2 + H2O Fe + Cl2 FeCl3

Hg + O2 HgO

H2 + Cl HCl

Mg + O2 MgO

O2 + H2 H2O

Fe + Cl2 FeCl3

CH4 + O2 CO2 + H2O

CAN YOU TELL WHICH IS A MOLECULE OF AN ELEMENT OR A COMPOUND CAN YOU TELL WHICH IS A MOLECULE OF AN ELEMENT OR A COMPOUND? WHICH SHOWS AN ATOM?

Examples: H2O, NaCl. MOLECULES ARE 2 OR MORE ATOMS ATTACHED TOGETHER THEY CAN BE THE SAME KIND (ELEMENTS) THEY CAN BE DIFFERENT KINDS (COMPOUNDS) Examples: H2O, NaCl.

Periodic Table: electron behavior The periodic table can be classified by the behavior of their electrons