Bellwork: Thursday 4/12/12 Take out Packet 10. Discuss your homework questions with students at your group. Be KIND to all ideas. We will share as a class in about 5 minutes. 1.Discuss the ethics of cloning only the best and brightest of the human race. 2.If you were in charge of undertaking a cloning project, which qualities would you look for when selecting your cloning subjects? Explain why.

Chemistry Review Atom- smallest particle of an element with the same properties as that element – In size the entire atom has been thought to be approximately four-billionths of an inch, meaning that approximately 250,000,000 atoms of this size must be put into line to span 1 inch. Element- matter made of one type of atom; cannot be broken down by chemical or physical means

Compound vs. Molecule Compound- matter made of two or more different elements; chemically bonded; cannot be separated by physical means; has properties different from elements that make it up – 6.2- THE STUDENT WILL EXPLAIN THAT COMPOUNDS FORM WHEN TWO OR MORE DIFFERENT KINDS OF ATOMS BOND. Molecule- matter made of two or more elements (same or different); smallest particle of a substance with the same properties as that substance – Heteroatomic molecule- must have more than one type of atom, such as water (H 2 O) and carbon dioxide (CO 2 ). – Homoatomic molecule- a molecule consisting of atoms of the same element; i.e. diatomic

Types of Molecules Diatomic Molecule- simplest molecule; two of the same atoms bonded together – H 2 O 2 F 2 Br 2 I 2 N 2 Cl 2 HOFBrINCl twins I Have No Bright Or Clever Friends Hydrogen; the rest form a 7 on the periodic table: N, O, F across, then going down Cl, Br, I. Polyatomic Molecule- Molecules containing more than two atoms are termed polyatomic molecules, e.g., carbon dioxide (CO 2 ) and water (H 2 O). – 6.4- THE STUDENT WILL COMPARE AND CONTRAST MOLECULES AND COMPOUNDS.

Physical and Chemical Changes are two basic ways that matter can change Think of elements as letters, and compounds as words: Physical Change – Printing the same word in a different type without changing the word Chemical Change – Rearranging the letters of the original word to make one or more new words – The new substances formed during a chemical change always have their own set of properties stampedes   made steps

Physical Properties and Physical Changes Physical Property observed with the senses (color, shape, odor, state/phase of matter) phase changes (melting point, boiling point, freezing point) Physical Change Physical changes are about energy and states of matter – You can cause physical changes with forces like motion, temperature, and pressure. MATTER: – Alters the form or appearance of a material – Does not make the material into a new substance; the matter is the same before and after the change – Original matter can be recovered; change can be “undone”

Physical Changes PARTICLES: – The molecules of the substance are rearranged, NOT atoms EXAMPLES: – chopping wood, bending copper wire into new shapes, painting a car, ice melting into water

Chemical Properties and Chemical Changes Chemical Property Observed during a chemical reaction; the way it reacts to another substance Based on the structure of the atoms or molecules Chemical Change any change that results in the formation of new substances MATTER: – The matter is different; the original matter is no longer present and cannot be recovered; the change cannot be “undone” – The substances present at the beginning of the change are not present at the end

Chemical Changes PARTICLES Bonds between atoms in molecules are broken, atoms are rearranged, and new bonds are made Forms a new substance with molecules with a different structure contains the same elements, but rearranged in new combinations – Synthesis Reaction: Element + Element  Compound  X + Y  XY – Decomposition Reaction: Compound  Element + Element  XY  X + Y – Single Displacement Reaction: Compounds  Compounds  A + XY  AY + X – Double Displacement Reaction: Compounds  Compounds  XY + AB  XB + AY EXAMPLES: Rusting of iron (oxidation), burning of gasoline in an engine (flammability)

Flammable vs. Combustible Flammable- material that can easily catch fire under normal circumstances and with the help of minimal ignition source. Just a spark is sufficient enough Flammable- material that can easily catch fire under normal circumstances and with the help of minimal ignition source. Just a spark is sufficient enough – Flash point: below 100°F – Example: gasoline, propane Combustible- material that will burn; but more vigorous conditions are required for an ideal combustible material to burn; A simple spark is definitely not enough. Combustible- material that will burn; but more vigorous conditions are required for an ideal combustible material to burn; A simple spark is definitely not enough. – Flash point: above 100°F – Example: paper, wood The distinction is determined by how easily they ignite The distinction is determined by how easily they ignite Flash point- the lowest temperature at which it can produce a flame when a source of ignition is present. Flash point- the lowest temperature at which it can produce a flame when a source of ignition is present.

Differentiating between physical and chemical properties… hold up 1 finger for physical, 2 fingers for chemical 1. Physical Property2. Chemical Property The color of the house is red. Oxygen is a gas. A flagpole is 25ft tall. Copper conducts electricity Iron reacts with water to form rust. Steel is attracted to a magnet. Silver reacts with moisture in the air to form tarnish.

Physical Chemical 1. Sulfur has a yellow color (Color) 2. Aluminum has a low density (Density) 3. Wood is combustible (Combustibility) 4. Zinc reacts with Sulfuric acid to form H 2 (Hydrogen gas) 5. Gasoline burns in the presence of oxygen (Flammable) 6. Sour Patch Kids ®candy has a sour taste (Taste) 7. Water melts at 0 degrees Celsius (Melting point) 8. Sodium (Na) + water (H 2 O) react to form Sodium hydroxide (NaOH) + Hydrogen gas (H 2 ) 9. Sodium hydroxide (NaOH - a base) + Hydrochloric acid (HCl) react to form water (H 2 O) + salt (NaCl) 10. Diamonds are capable of cutting glass (Hardness) 11. Water boils at 100 degrees Celsius (Boiling point) 12. Acetic acid (C 2 H 4 O 2 ) can neutralize a base 13. Pyrite, aka Fool’s Gold, has a metallic luster (Luster) 14. Arsenic’s odor is similar to garlic (Odor) 15. Baking soda, aka Sodium bicarbonate (NaHCO 3 ), reacts with vinegar (HC 2 H 3 O 2 ) to produce Carbon dioxide gas (CO 2 ) 16. Antimony has a flaky, crystalline texture (Texture) 17. An ounce of gold can be hammered into a square sheet 100 feet on each side (Malleability) or drawn into a wire that would stretch 5 miles (Ductility) 18. Silver’s ability to oxidize gives it a unique look, popular in jewelry making (Oxidation) 19. Water can be separated by electrolysis into hydrogen and oxygen (2 H 2 O(l) → 2 H 2 (g) + O 2 (g) 20. Mercury is liquid at room temperature (State of Matter) TSW CLASSIFY SUBSTANCES USING THEIR PROPERTIES. X X X X X X X X X X X X X X X X X X X X

Evidence that a Chemical Change has Occurred: Page 4 1.B ubbles of gas appear 2.A precipitate (solid) forms 3.A color change occurs 4.T he temperature changes 5.L ight is emitted 6.A change in volume occurs 7.A change in electrical conductivity occurs 8.A change in melting point or boiling point occurs 9.A change in smell or taste occurs

Homework: Packet 11, Page 3 Due tomorrow Physical vs. Chemical Changes BOTTOM: Choose 2 examples of physical changes, and 2 examples of chemical changes. Explain why you chose chemical or physical. Support your explanation with examples or proof. Burning trees are chemically changed into other substances like carbon and ash.

Bellwork: Friday 4/13/2012 List (2) possible observations that might make Angelina think she observed a physical change. – No change occurs in the identity of the substance – Color changes – Size/Shape changes – Phase changes (solid, liquid, or gas/condensation) List (9) possible observations that might make Angelina think she observed a chemical change. – Atoms are rearranged to form different substances 1.Bubbles of gas appear 2.A precipitate (solid) forms 3.A color change occurs 4.The temperature changes 5.Light is emitted 6.A change in volume occurs 7.Electrical conductivity change 8.Melting/boiling point change 9.Odor or taste change Angelina performed two chemistry experiments in her science class. In the first experiment, she thought she observed a physical change. In the second experiment, she thought she observed a chemical change.

Changes in Energy in Chemical Reactions Endothermic- energy is absorbed – Ex. Cold pack, baking bread Exothermic- energy is released – Ex. Burning gasoline, fireworks

Chemical and Physical Change Equations Physical: G + B  GB Same atoms on both sides of the equation Chemical: A + B  C Different substances on both sides of the equation. A & B on the left form a completely different substance C on the right. Reactants: left side (what is reacting; A & B) Products: right side (what is produced; C)

Law of Conservation of Mass Matter can neither be created or destroyed, but can be changed in form. The total mass of the material(s) before the reaction is the same as the total mass of material(s) after the reaction. The total mass of the material(s) before the reaction is the same as the total mass of material(s) after the reaction. Mass of Reactants = Mass of Products

“+” read as “plus” – Separates molecules on the same side “  ” read as “yields” – Separates reactants (left); products (right) Numbers in front: coefficients Physical states of compounds Solid (s) Liquid (l) Gas (g) Aqueous solution (aq) Escaping gas (  ) Change of temperature (  ) Symbols Used in Equations

Types of Chemical Reactions Synthesis Reaction: Element + Element  Compound  X + Y  XY Decomposition Reaction: Compound  Element + Element  XY  X + Y Single Displacement Reaction: Element + Compound  Compound + Element  A + XY  AY + X Double Displacement Reaction: Compound + Compound  Compound + Compound  XY + AB  XB + AY

Synthesis Decomposition H 2 CO 3  H 2 O + CO 2 2 Na + Cl 2  2 NaCl

Double Displacement Single Displacement NaCl + AgF  NaF + AgCl Zn + 2HCl  ZnCl 2 + H 2

REVIEW: Law of Conservation of Mass- Packet 12, Page 4 Matter is never created or destroyed in chemical reactions. The particles of one substance are rearranged to form a new substance. The same number of particles that exist before the reaction exist after the reaction. Why do we need a rubber stopper in the flask? Mass of Reactants = Mass of Products

Chemical Equations Charcoal used in a grill is Carbon. Carbon reacts with oxygen gas to make carbon dioxide. Charcoal used in a grill is Carbon. Carbon reacts with oxygen gas to make carbon dioxide. What is the chemical equation for this reaction? What is the chemical equation for this reaction? C + O 2  CO 2 – This reads “carbon plus oxygen gas react to yield carbon dioxide”

Because of the Law of Conservation of Matter, an equation must be balanced. It must have the same number of atoms of the same kind on both sides. Balancing Chemical Equations

1.Write correct formula for reactants & products. 2.Find the # of atoms for each element on the left and right. 3.Add coefficients in front of formulas so the left has the same # of atoms as the right HINT: Work on one element at a time DO NOT CHANGE THE FORMULAS! You may not change the subscripts Changing the subscripts changes the compound. 4.Check your answer to see if: – The # of atoms on both sides of the equation are now balanced – The coefficients are reduced to the least common factor Steps to Balancing Equations- Page 5

1.Correct Formula 2.Find # of atoms on left and right List atoms involved on each side of the arrow Count up the atoms on each side 3. Add coefficients- adjust totals Totals still aren’t equal Add coefficients- adjust totals 4.Check Answers Mg O Mg+O 2  MgO BOTH SIDES HAVE EQUAL NUMBERS OF ATOMS WE SAY THAT THE EQUATION IS BALANCED!! What type of rxn is this? Synthesis- S

Fe 3 O H 2  3 Fe + 4 H 2 O 1. Number of H atoms in 4 H 2 O a) 2 b) 4 c) 8 2. Number of O atoms in 4 H 2 O a) 2 b) 4 c) 8 3.Number of Fe atoms in Fe 3 O 4 a) 1 b) 3 c) 4 Balancing Equations Quick Check

Practice Balancing Equations 1.Mg+N 2  Mg 3 N 2 a) 1, 3, 2 b) 3, 1, 2 c) 3, 1, 1 3 Mg+N 2  Mg 3 N 2 2.Al+Cl 2  AlCl 3 a) 3, 3, 2 b) 1, 3, 1 c) 2, 3, 2 2 Al+3 Cl 2  2 AlCl 3 Balance each equation. The coefficients for each equation are read from left to right What type of rxns are these? Synthesis- S

Fe 2 O 3 +C  Fe+CO 2 a) 2, 3, 2, 3 b) 2, 3, 4, 3 c) 1, 1, 2, 3 2 Fe 2 O C  4 Fe+ 3 CO 2 Al+FeO  Fe + Al 2 O 3 a) 2, 3, 3, 1 b) 2, 1, 1, 1 c) 3, 3, 3, 1 2 Al+ 3 FeO  3 Fe+Al 2 O 3 Al+H 2 SO 4  Al 2 (SO 4 ) 3 + H 2 a) 3, 2, 1, 2 b) 2, 3, 1, 3 c) 2, 3, 2, 3 2 Al+ 3 H 2 SO 4  Al 2 (SO 4 ) H 2 What type of rxns are these? Single Displacement- SD

Burning of Propane C 3 H 8 + 5O 2  3CO 2 + 4H 2 O 1, 5, 3, 4 Combustion of Hydrogen and Oxygen, which is a commonly used reaction in rocket engines: 2H 2 + O 2 → 2H 2 O 2, 1, 2 Combustion reaction with Fluorine as an oxidizing agent: CH 2 S + 6F 2 → CF 4 + 2HF + SF 6 1, 6, 1, 2, 1 Burning of Methane CH O 2 → CO 2 + 2H 2 O 1, 2, 1, 2 Photosynthesis 6H 2 O + 6CO 2  C 6 H 12 O 6 + 6O 2 6, 6, 1, 6

Homework- Pages 7 & 8: Balancing Chemical Equations & Types of Reactions Work silently on these pages