Test Review PowerPoint for 4th Period

Reactants and Products Reactants are combined together to create products What are the reactants and products in the following equations? C + 2O CO2 2H + O H2O Reactants Product Products Reactant What do you notice about these equations? Coefficients-big numbers (in front) Subscripts-small numbers (behind)

Chemical Equations Label the reactants and products on the chemical equation below: CaCO3 CaO + CO2 Reactants Products

Label the reactants and products. On the practice worksheet. Mg + O2 MgO 2H2O2 2 H2O + O2 2Cu2O + C 4Cu + CO2 FeS + 2HCl FeCl2 + H2S P4O10 + 6H2O 4H3PO4 Fe2O3 + C Fe + CO2 SO2 + O2 SO3

Conservation of Mass You must end up with the same amount you started with. Mass cannot be created or destroyed

Conservation of Mass Matter is not created or destroyed

Balancing Equations Goal- Have the same number of atoms on both sides of the equation. Rules Coefficients (numbers in front) multiply You can not change subscripts (numbers behind) If there is no subscript after an atom, then you know there is only 1 atom present

Balancing Equations 1. Write equation 2. Count Atoms H O H O 2 2 2 1

Balancing Equations 3. Use coefficients to balance the equation 4 2 H O 2 H O 2 2 2 4 1 2 3. Use coefficients to balance the equation

H O 2 2 H O 4 2 4

Balancing Equations Practice 2 2 H2 + O2  H2O H2 + Cl2  HCl SO2 + O2  SO3 Mg + O2  MgO 2 2 2 2 2

How do we make the reaction go faster? There are four things that we can change to make the reaction go faster. They are Temperature Surface area Concentration Using a catalyst

1. Temperature When we increase the temperature we give the particles energy This makes them move faster This means they collide with other particles more often So the reaction goes faster.

2. Surface area If we make the pieces of the reactants smaller we increase the number of particles on the surface which can react. This makes the reaction faster. The particles on the surface can react When cut into smaller pieces the particles on the inside can react

3. Concentration If we make one reactant more concentrated, there are more particles in the same volume to react So the reaction goes faster. There are less red particles in the same volume so there is less chance of a collision There are more red particles in the same volume so there is more chance of a collision so the reaction goes faster http://www.youtube.com/watch?feature=player_embedded&v=kjKyEdrVXJA

4. Using a catalyst A catalyst is a chemical which is added to a reaction. It makes the reaction go faster. The catalyst does not get used up in the reaction. It gives the reaction the energy to get started

Enzyme catalyst http://www.youtube.com/watch?v=XX9Xo6zm_kM&feature=player_detailpage

Elements Made of atoms of one kind The type of element depends on the atomic number, or the number of protons it has Most elements occur naturally, but some have to be created in a lab

Periodic Table Elements are organized on the Periodic Table according to atomic number and properties of the element Open textbook to pages L14 – L15

Symbol The abbreviation letters used for each element

Atomic Number Number of protons (each element has a different # of protons) Number of electrons (same as # of protons so the element is electrically neutral)

Atomic Mass atomic mass ( rounded) – atomic number Mass of the Atom or # of the protons plus neutrons Each proton equals 1 amu and each neutron equals 1 amu (atomic mass unit) How do you find the average number of neutrons in an atom? atomic mass ( rounded) – atomic number

Groups Groups: or Family = columns Share similar properties Numbers on top indicate what group it is Noble gases-Group 18 (or 8A) Halogens-Group 17 (or 7A) Alkali metals-Group 1

Periods Periods = rows Atomic mass increases from left to right Number of protons increases from left to right Number of electrons in the outer shell of the atom increases from left to right Only hydrogen and helium are in the 1st period

Look at L14 –15 or L186 – L187

Physical Properties description Physical properties can be observed or measured without changing the identity of the matter. They are determined by the use of the They are a of an object. Five senses description

Examples of Physical Properties Color Smell Taste Hardness State of Matter (solid, liquid or gas) Boiling, Freezing, or Melting Point

Examples of Physical Properties Density Mass Volume Conductivity - The ability of a substance to allow the flow of energy or electricity.

Physical vs. Chemical Physical properties: observe without changing the identity of the substance Chemical properties: observe only when the identity changes How do you know if it is chemical or physical? If it CHanges, it’s CHemical Combustion of Mg strip https://www.youtube.com/watch?v=EZ3JT2nWfMA

Chemical Properties react Are determined by a substance’s ability to _______with other substances. react

Chemical properties Reactive to oxygen Reactive to air A common chemical property is reactivity. Reactive to oxygen Reactive to air Reactive to water… Reactive to acid Notice that chemical properties aren’t EASY to observe, unlike physical properties.

Examples of Chemical Properties air The ability to react with , _______, _________, __________ The ability to catch fire ( ) rust tarnish corrode rot Water or acids flammability

Physical or Chemical Property? 1. Ability of gun powder and fire to explode. Chemical Property

Physical or Chemical Property? 2. The color of a sunset. Physical Property

Physical or Chemical Property? 3. The ability of a nail to rust. Chemical Property

Physical or Chemical Property? 4. The shape of a leaf. Physical Property

Physical or Chemical Property? 5. The ability of wood to burn. Chemical Property

Physical or Chemical Property? 6. The hardness of a diamond. Physical Property

Physical or Chemical Property? 7. The volume of your soda. Physical Property

Physical or Chemical Property? 8. The mass of two camels. Physical Property Complete Physical and Chemical Properties worksheet in your packet – page 5

Atoms Modern Atom Model Nucleus-Protons and Neutrons Electrons around nucleus, never know the true location

Protons Positively charged particle In nucleus Mass 1 amu

Neutrons Neutral (no) charge particle In nucleus Mass 1 amu

Electrons Negatively charged particle In electron cloud (orbitals) around the nucleus Mass 0 amu

Chemical Changes A change in matter that results in one or more new substances. You change what it is. Chemical in the original substance combines with another chemical to create a new substance

Evidence of Chemical Reactions or Change https://www.youtube.com/watch?v=cZMkqagL8Ps (2:52) Evidence of a Chemical Reactions

Evidence of Chemical Change New ________appears Bubbbles or ________ Precipitate forms (____ material) color _____ is produced ______ is produced ______ is given off Heat fizzing Light Sound solid Difficult or impossible to __________ reverse