10-12-09Bell Work

Draw a picture of Cl and Sodium using what we learned in class on Friday. Include electrons,

protons, neutrons, energy levels, valence electrons. Put all of the subatomic particles in

the correct place.

Recap on Periodic Table

• The numbers 1A, 2A, 3A are the valence electrons

• Valence electrons are electrons on the outermost energy level

• Valence shell is the outer most energy level.

Chemical Reactions

• Involve breaking bonds

• Breaking bonds requires energy

• Forming bonds releases energy

• Energy is released when bonds are formed

Endothermic vs. Exothermic Reaction

• Sunset in A Bag

• Bag got warm-Bag got warm- exothermic reaction-energy is released; increase in temperature

• Bag got cold-Bag got cold- endothermic reaction-reaction absorbs energy.

The periodic table is a map of elements

• MetalloidMetalloid-elements that have properties of both metal and non-metals; are on either side of zigzag line; most common is silicon; found in electronics; semiconductors that are used in computer chips

Recap – Valence Electrons

• Outside energy level

• Atoms with shells that are not full are more likely to bond (stick together) with other elements

• Look at numbers 1A, 2A …these are the valence numbers.

• There is a nifty way to draw these valence numbers…called Lewis Dot.

10-13-09 Bell Work – Enter into TOC-

• 1. Which elements on the periodic table (pick three) have only 1 valence electron?

• After you draw them (pick ones with less than 18 protons) then label the valencelabel the valence electrons and valence shell.

• How likely are these elements to bond with other elements? Explain your thinking. 1 complete sentence.

Lewis Dot Pictures

• Group 1

• Group 2

Lewis Dot

• Group 5

• Group 6

Lewis Dot Pictures

• Group 3

• Group 4

Lewis Dot Structures

• Group 7

• Group 8

Chemical Equations

• Arrow-Arrow- means yields or equals

Practice Problems

Review Chemical Equations 10-12-09

• Concepts: Subscript, Coefficient, Product, Reactant, Yield

• Subscript- number of atoms of an element

• CoefficientCoefficient- number in front of molecule• ReactantsReactants- what starts the chemical

reaction• ProductProduct- what is made in a chemical

reaction

Forming Positive Ions

• Example: Sodium. How many electrons does sodium have? ____ How many protons? ____

• What would happen if sodium lost one electron? What would be the overall charge for the atom? ______

Forming Negative Ions

• Chlorine. What is the number of protons? ______ electrons? _____ neutrons_____

• What would happen if an electron was ADDED to the chlorine atom? _____

• What would the overall charge be for this atom?_____

Practice Problems

10-14-09 Bell Work- put in ISN in your TOC

• Mrs. Antkowiak wants to know how fertilizer will impact the growth of her Connecticut pumpkins. She gives 10 pumpkin plants 50g of fertilizer mixed in 30 ml of water each Saturday. The other 10 pumpkin plants receive no fertilizer. Answer the following questions:

• What is the independent variable, dependent variable, control group and what are some controlled variables?

What we are doing Today

• Benchmark- Exam in class

• No talking

• Need Pencil

• When you are done you are to read without talking.

How to turn in benchmark

• Turn in benchmark and answers in a different stack- face down on the table.

• Do not mark on the benchmark

• You may mark on your answer sheet only

• Bubble your name and write your name in.

• You need to use pencil.

• Erase well.

10-19-09

• Bell Work- goes in ISN

• What is an ion?

• How is an ion formed?

• What would happen if you lost an electron, would the atom become more negative or more positive?

Atoms form Ions

• An atom has an equal number of electrons and protons; they have no overall charge.

• Exception to the rule

• An ION- is formed when an atom LOSES or GAINS one or more electrons; this causes an overall charge that it either positive or negative.

How to represent ions

• When an atom has a negative charge you put a - sign to the right of the symbol.

• When an atom has a positive charge you put a + sign to the right of the symbol.

• If an atom gains more than one electron, the number of added electrons is shown by a number in front of the minus sign. example______, ____, _______

Ion- charged particle

• Atoms that do not have a full valence shell will bond with other atoms

• Atoms on the left sideleft side of the periodic table will bond with other elements because they only have one valence electron

• Atoms behave a certain way based on the number of electrons on the outside energy level

10-20-09• What is the Law of Conservation of

Mass- explain in your own words?

• If you have 10g of Na and 5g of C (your reactants), what should you have at the end ofend of the chemical reaction with the amount of product leftproduct left over? Explain.

Law of Conservation of Mass

• You will have the same number of atoms at the end of a chemical reaction as you did in the beginning.

• Example: If you start out with • 10CO2 -------- 10 C + 10O2

Example Conservation of Mass

• 22 grams of Sodium reacts with 52 grams of Chloride to make NaCl.

• How much NaCl is made in the experiment?

Chemical Bonds between atoms involve electrons

• Chemical bonds – like glueglue that holds atoms of elements

together in compounds.

– form when electrons in electron shells interact

• - effect chemical and physical properties of compounds

Ionic BondsIonic Bonds

• When a positive ion and a negative ion atom stick together.

• NaCl

• Salt

• Opposites attract

Ionic Bonding- Sodium Chloride

Ionic Bonds• - positive ions are strongly

attracted to the negative ions• - the new substance formed does

not resemble either of the original atoms

• - this attraction binding unlike ions together is called ionic bonding

•  example: CaF2

Covalent Bonds

• Atoms can shareshare electrons

• Neither atom gains or loses an electron

• No ions are formed

Covalent Bonds

• - HYDROGEN, CARBON, NITROGEN, AND OXYGEN are noted for forming covalent bonds

•  single covalent bond:      

•  double covalent bond:

•  triple covalent bond:

Covalent Bond

Making Meaning of It• Atomic Number- # of protons• Atomic Mass- # of Neutrons and Protons

• If the number of protons changes then you will have a totally different element !!!

• Some atoms will have a different numberdifferent number of neutrons than an atom of the same element.

Isotope• An atom of one element that has

different number of neutronsdifferent number of neutrons than another atom of the same element

• Isotopes have different numbers of neutrons

• Ex: Chlorine (35 neutrons) (37 neutrons

Chemical Reactions Wrap It Up

• Precipitate- Precipitate- a solid substance that forms as a result of a reaction between chemicals in two liquids

• CatalystCatalyst-a substance that increases the rate of a chemical reaction but is not used up during the chemical reaction

Boiling Point• temperature at which a liquid changes to a gasliquid changes to a gas (vapor) at normal atmospheric pressure. ...

Melting Point•The melting point of a solid is the temperature range at which it changes state from solid to liquid

Freezing Point•For any given liquid, the temperature at which the liquid changes state from a liquid to a solid.

Main Ideas• Compounds have different properties from

the elements that made them

• Chemical bonds between atoms involve electrons

• Atoms can transfer electrons

• Atoms can share electrons

• Chemical bonds give all materials their structure

Main Ideas

• Metals have unique bonds• Ionic and covalent bonds

give compounds certain properties

• Bonds can make the same element look different

Main Ideas• Mass is conserved in chemical reactions

• Chemical equations summarize chemical reactions

• Balanced chemical equations show the conservation of mass

• You have the same amount of atoms in the beginning of a reaction as you do at the end of a reaction

Main Ideas• All matter is made of atoms

• Different elements are made of different atoms.

• Atoms form ions by gaining or losing electrons.

• Periodic table organizing atoms of elements by properties and atomic number.

• Most elements are metals