Bell 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.

Bell Work – Enter into TOC- 1. Which elements on the periodic table (pick three) have only 1 valence electron? label the valenceAfter you draw them (pick ones with less than 18 protons) then label 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 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

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.

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 left sideAtoms on the left 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

What is the Law of Conservation of Mass- explain in your own words? end of product leftIf you have 10g of Na and 5g of C (your reactants), what should you have at the end of the chemical reaction with the amount of product 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 10CO 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 glue –like glue that holds atoms of elements together in compounds. –form when electrons in electron shells interact - effect chemical and physical properties of compounds

Ionic 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 shareAtoms can share 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 !!! different numberSome atoms will have a different number of neutrons than an atom of the same element.

Isotope different number of neutronsAn atom of one element that has different 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 liquid changes to a gastemperature at which a liquid 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 liquidstateliquid

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