Chemical Reactions Intro

When you are balancing a chemical reaction, do you change the coefficients or subscripts? Identify how many atoms are in the following molecule: 3PO4. Label the products and reactants in the following equation. N 2 + H2  NH3 Warm-Up Agenda: -warmup -Review Beads Lab --Snowman Challenge -Exit Slip

WarmUp Name the 3 subatomic particles found in an atom. Please take a NEW warmup sheet AND table of contents from the front table! WarmUp Name the 3 subatomic particles found in an atom. Which of these three are the ONLY particles involved in chemical bonding? Describe the difference between ionic and covalent bonding. Proton, neutron, electron electron Ionic: transfer of electrons Covalent: sharing of electrons

Intro to chemical reactions https://www.youtube.com/watch?v=dUMmoPdwBy4

Chemical Reactions Occur when there is a transfer or sharing of electrons Chemical reactions occur when two chemicals unite or react to form a compound that is unlike the original substances and cannot be changed back to its original form. When a chemical reaction occurs, the substances involved undergo a chemical change

Chemical Changes Evidence of chemical change: bubbling (formation of gas) turning cloudy (formation of a new solid) temperature change (heat or light released) color change (formation of a new solid)

Chemical Reactions In chemical reactions you start with reactants that are combined into products. The reactants and products may include atoms, molecules, and energy.

Chemical Reactions The formation of rust from oxygen and iron is an example of a common chemical reaction.

Chemical Reactions Chemical reactions proceed in two stages. 1. First, the chemical bonds must be broken between the atoms in the reactants. 2. In the second stage, new bonds form between atoms to make the products of the reaction.

Activation energy The energy needed to break chemical bonds in the reactants is called the activation energy of the reaction. A spark supplies the activation energy to start the reaction between hydrogen and oxygen.

Mass in chemical reactions A balanced chemical equation is like a recipe. The mass of the products must equal the mass of the reactants. Counting molecules is not practical so we usually need the mass of reactants and products of a chemical reaction.

Chemical Reactions REMINDER: The law of conservation of mass states that in a chemical reaction matter is not created or destroyed but conserved. This means that however many atoms you start with (reactants), you will end with the same amount of atoms (products)

Chemical Formula Reactants are the substances that chemically combine yield Reactants are the substances that chemically combine Products are the new substances formed

Chemical Formula Subscripts indicate the number of atoms needed for a compound. Coefficients represent the number of units of each substance taking part in a reaction 2H2 (g) + O2 (g)  2H2O (l) Coefficient Subscript

WarmUp P = 3 O = 12 What is needed to start a reaction? Agenda: -WarmUp -Review Popcorn Lab -Balancing Reactions with Beads Please send 1 person up to my computer to enter popcorn data!! WarmUp What is needed to start a reaction? What does the law of conservation of mass state? Identify how many atoms are in the following molecule: 3PO4. Activation energy to break bonds so they can reform into their new compounds/molecules Mass cannot be created nor destroyed P = 3 O = 12

Review law of Conservation of mass Watch this https://www.youtube.com/watch?v=2S6e11NBwiw Let’s talk about your lab Watch this! http://www.nytimes.com/video/science/10000000351001 6/the-physics-of-popcorn.html

Let’s Practice Balancing!!

Balancing Act Practice Agenda: -warmup -finish Beads Lab Counting atoms Balancing Act Practice WarmUp Explain why a chemical equation must be balanced. Name two indications that a chemical reaction has occurred. List the two steps of a chemical reaction To show no matter (mass) was created or destroyed Bubbles, color change, temperature change, becoming cloudy 1) Energy is needed to break bonds present 2) New bonds are formed between what was broken apart