* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Unit 1 Matter Day 32 2016 Counting Atoms
Process chemistry wikipedia , lookup
Chemical biology wikipedia , lookup
Computational chemistry wikipedia , lookup
American Chemical Society wikipedia , lookup
Chemical reaction wikipedia , lookup
Chemical equilibrium wikipedia , lookup
Physical organic chemistry wikipedia , lookup
Chemical warfare wikipedia , lookup
Gas chromatography–mass spectrometry wikipedia , lookup
Determination of equilibrium constants wikipedia , lookup
Isotopic labeling wikipedia , lookup
Fine chemical wikipedia , lookup
Destruction of Syria's chemical weapons wikipedia , lookup
Chemical element wikipedia , lookup
Transition state theory wikipedia , lookup
Chemistry: A Volatile History wikipedia , lookup
California Green Chemistry Initiative wikipedia , lookup
Chemical imaging wikipedia , lookup
Chemical bond wikipedia , lookup
Molecular dynamics wikipedia , lookup
Drug discovery wikipedia , lookup
Safety data sheet wikipedia , lookup
Al-Shifa pharmaceutical factory wikipedia , lookup
Chemical potential wikipedia , lookup
IUPAC nomenclature of inorganic chemistry 2005 wikipedia , lookup
Chemical weapon proliferation wikipedia , lookup
Chemical plant wikipedia , lookup
Chemical weapon wikipedia , lookup
Chemical industry wikipedia , lookup
Chemical Corps wikipedia , lookup
Stoichiometry wikipedia , lookup
History of chemistry wikipedia , lookup
Atomic theory wikipedia , lookup
History of molecular theory wikipedia , lookup
UNIT 1 MATTER DAY 32 OCTOBER 14, 2016 Counting Atoms 8th Grade Science OCTOBER 14, 2016 3rd period – I need 2 students to play the “Ships and Sailors” game at the pep rally today. Santi and Zac are still doing the relay. 4th period – No walk today. Figure it out! Pick up a copy of the notes “Law of Conservation of Mass/Balancing Chemical Equations” from the lab table, and be seated. Plan for today: 1. Lesson on chemical formulas and chemical equations 2. Practice counting atoms in compounds 3. 4th period – Review quiz on elements, compounds, and mixtures 4. Bill Nye “Chemical Reactions” video, if time permits Homework: Worksheet “How to Count Atoms” and “Counting Atoms”. E.Q Page _____ How do balanced chemical equations demonstrate the Law of Conservation of Matter? CHEMICAL FORMULAS Def. Chemical formula is a combination of chemical symbols and numbers to represent a substance.It shows how many atoms of each kind of element are present in a molecule. Subscript: a number written to the lower right of a chemical symbol. It tells how many atoms of that element are present. Copy these 3 examples. CHEMICAL EQUATIONS •Def. Use chemical symbols and formulas to describe a chemical reaction. •Ex: Copy this Chemical equation. •C and O2 are the reactants. CO2 is the product. yields *Coefficient: a number that is placed in front of a chemical symbol or formula in order to balance a chemical equation. Subscripts (the little numbers) CANNOT be changed to balance an equation. Why? H 2O CO2 C6H12O6 2H20 -2 molecules of water 4CO2 – 4 molecules of carbon dioxide RULES FOR COUNTING ATOMS: Subscripts (the little numbers) tell you how many atoms of that element are present. H2O = 2 atoms of hydrogen and one atom of oxygen If a coefficient (big number) is written in front of a chemical formula or symbol, you have to multiply that number by all the elements in the compound. Ex. 2NaCl (think about the distributive property in math) 2(NaCl) – this would mean 2 atoms of sodium (Na) and 2 atoms of chlorine (Cl) OR 2 molecules of sodium chloride If a compound contains subscripts and coefficients, you have to multiply the coefficients by the subscripts. Ex. 2Na2SO4 or 2(Na2SO4) = 4 sodium (Na) atoms, 2 Sulfur atoms, and 8 oxygen atoms LET’S PRACTICE COUNTING ATOMS IN PREPARATION FOR LEARNING HOW TO BALANCE CHEMICAL EQUATIONS. STOP HERE – SHORT CLASSES DUE TO PEP RALLY CHEMICAL FORMULAS Def. Chemical formula is a combination of ____________ ___________and ____________ to represent a ___________.It shows how many __________ of each kind of ___________ are present in a ____________. Subscript: a number written to the _________ __________ of a chemical ___________ . It tells how many ___________ of that element are present. CHEMICAL EQUATIONS •Def. - Use chemical ____________ and ____________ to describe a ____________ ____________. LAW OF CONSERVATION OF MASS Def. This law states that matter(mass) CANNOT be created or destroyed in ordinary physical or chemical changes. The total mass of the reactants equals the total mass of the products. This can be proven in a closed system… one in which nothing enters or leaves the system. LAW OF CONSERVATION OF MASS Def. This law states that ______________ CANNOT be _____________ or _____________ in ordinary ______________or ________________ ________________. The total __________________________________________ ______________________________________________________. This can be proven in a __________ ___________…one in which nothing enters or leaves the system. Let’s look at the Law of Conservation of Mass and Chemical Equations presented Brainpop’s way. Brainpop - Law of Conservation of Matter A Quick Review elements Chemical symbols represent __________. compounds Chemical formulas represent __________. chemical reactions. Chemical equations represent __________. Now let’s learn how to balance chemical equations. A Quick Review Chemical symbols represent __________. Chemical formulas represent __________. Chemical equations represent __________. Now let’s learn how to balance chemical equations. *Coefficient: a number that is placed ____________ a chemical _________ or _________ in order to __________ a chemical ___________. Subscripts __________ be _________ to balance an equation. Why? H2 O CO2 C6H12O6 2H20 -2 molecules of water 4CO2 – 4 molecules of carbon dioxide More O2 in the reactants. Count to be sure the number of atoms of each element is the same in the reactants and products. How to Balance Chemical Equations: 3 Simple Steps Step 1: Count the number of atoms for each element on both sides of the equation. Look for elements that are not balanced. Ex. Mg + O2 MgO- _____ is unbalanced. MgO MgO- Step 2: Add a coefficient in front of the formula that contains the unbalanced element(s). The O was unbalanced. Place a coefficient 2 in front of the MgO. ***Note: This may throw off the balance of other elements, so you have to keep working with it. Ex. Mg + O2 __ MgO This will balance the O, but unbalance the Mg. So…add another coefficient 2 in front of the Mg in the reactant. Ex. ___Mg + O2 2 MgO *This should balance the Mg but be sure to do Step 3. Step 3: Check the number of atoms on both sides of the equation to be certain they are balanced. 2Mg + O MgO- 2MgO MgO- Is it balanced? If so, you have supported the Law of Conservation of Matter (Mass). How does balancing equations illustrate and support the Law of Conservation of Mass/Matter? *Because they require that you have the same mass after the reaction as you do before the reaction. This means… *The # and type of atoms are the same in the reactants and products (just in different combinations) *Although the state of matter of the products may be different from the reactants, the overall mass doesn’t change. Let’s look at Chemical Equations presented Brainpop’s way. Brainpop-Chemical Equations Before we practice balancing equations, let’s practice counting atoms. Practice Counting Atoms worksheet Let’s practice balancing some chemical equations. “Balancing Act” practice sheet. Use pencil. You may have to change coefficients a few times. In a chemical reaction, no atoms are gained or lost. They just get rearranged. Because this Law of Conservation of Matter (Mass) has been proven, chemical equations (which represent a chemical reaction) MUST be balanced (same number of atoms on both sides). mass of the reactants=mass of the products. Wrap-up: Any questions?