Section 1: Forming New substances
Vocabulary
1) Chemical Reaction: the process by which one or more substances change to produce one or more different substances
2) Precipitate: a solid that is produced as a result of a chemical reaction in solution
2) Precipitate: a solid that is produced as a result of a chemical reaction in solution
section summary
This section was about forming new substances. New substances are formed when chemical reactions (vocabulary word one) take place, and the chemical and physical properties of the new substances differ from those of the original substances. Signs of a chemical reaction include gas formation , solid formation (Precipitate: vocabulary word one), color change, and energy change (energy may be given off in the form of light, thermal energy, or electric energy). Reactions may even display more than one of these signs. Also, if a new substance is formed that has different physical and chemical properties then it is a new substance.
Lastly, bonds hold molecules together. A chemical bond is a force that holds two atoms together in a molecule. Making and breaking bonds both require a large amount of energy.
Lastly, bonds hold molecules together. A chemical bond is a force that holds two atoms together in a molecule. Making and breaking bonds both require a large amount of energy.
Section 2: Chemical formulas and equations
vocabulary
1) Chemical Formula: a combinatio of chemical symbols & numbers to represent a substance
2) Chemical Equation: a representation of a chemical reaction that uses symbols to show the relationship between the reactants and the products
3) Reactant: a substance or molecule that participates in a chemical reaction
4) Product: the substances that forms in a chemical reaction
5) Law of Conservation of Mass: the law that states that mass cannot be created or destroyed in ordinary chemical and physical changes
2) Chemical Equation: a representation of a chemical reaction that uses symbols to show the relationship between the reactants and the products
3) Reactant: a substance or molecule that participates in a chemical reaction
4) Product: the substances that forms in a chemical reaction
5) Law of Conservation of Mass: the law that states that mass cannot be created or destroyed in ordinary chemical and physical changes
section summary
This section was about chemical formulas and equations. A chemical formula (vocabulary word 1) shows how many atoms of each element are present in each molecule. A subscript is a number written below and to the right of a chemical symbol in a chemical formula, but if there is no subscript present then there is only one atom of the element (H2O: Two hydrogen atoms & one oxygen atom). Formulas for covalent compounds can also be identified by their prefixes (mono=1, di=2, tri=3, tetra=4, penta=5, hexa=6, hepta=7, octa=8, nona=9, deca=10). The prefixes are also used to identity the number of atoms of a certain element are present. However, to write the formula for an ionic compound, the overall charge must be zero.
Chemical equations (vocabulary word 2) are composed of reactants (vocabulary word 3). The
reactants in a chemical equation are separated by a plus sign, and an arrow
leads to the new product (vocabulary word 4). Accuracy is important in these equations because a
wrong letter a number can completely change the element/compound. The equations
must also be balanced.Balancing an equation properly displays the law of
conservation of mass (vocabulary word 5), which states that mass can never be created or
destroyed. Equations are balanced by having the same number of atoms of each
type of element present on both sides of the equation.
reactants in a chemical equation are separated by a plus sign, and an arrow
leads to the new product (vocabulary word 4). Accuracy is important in these equations because a
wrong letter a number can completely change the element/compound. The equations
must also be balanced.Balancing an equation properly displays the law of
conservation of mass (vocabulary word 5), which states that mass can never be created or
destroyed. Equations are balanced by having the same number of atoms of each
type of element present on both sides of the equation.
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Section 3: types of chemical reaction
vocabulary
1) Synthesis Reaction: a reaction in which two or more substances combine to form a new compound
2) Decomposition Reaction: a reaction in which a single compound breaks down to forms two or more simpler substances
3) Single-Displacement: a reaction in which one element or radicaltakes the place of another element or radical in a compound
4) Double-Displacement: a reaction in which a gas, a solid precipitate, or a molecular compound forms from the exchange of ions between two compounds
2) Decomposition Reaction: a reaction in which a single compound breaks down to forms two or more simpler substances
3) Single-Displacement: a reaction in which one element or radicaltakes the place of another element or radical in a compound
4) Double-Displacement: a reaction in which a gas, a solid precipitate, or a molecular compound forms from the exchange of ions between two compounds
section summary
This section was about types of chemical reactions. The first kind of reaction is a synthesis reaction (vocabulary word 1), which is when two or more substances combine to form one new compound (Ex: 2Na + Cl2 --> 2NaCl) The next type is a decomposition reaction (vocabulary word 2), which is when a single compound breaks down to form two or more simpler substances (Ex: H2CO3 --> H2O + CO2). Next, are single-displacement reactions (vocabulary word 3), which are when one element replaces another in a compound (Ex: Zn + 2HCl --> ZnCl + H2). The product of a single-displacement reaction would be a different element and a new compound. Also, sometimes in a single-displaceent reaction, a more reactive element may replace a less reactive element in a compound. Only Group 17 nonmetals (out of all nonmetals) participate in single-displacement reactions. Lastly, are double-displacement reactions (vocabulary word 4). In a double-displacement reaction ions from two compounds exchange places with each other to form new compounds (Ex: NaCl + AgF --> NaF + AgCl). One of the products of this type of reaction is often a gas or a precipitate.
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Section 4: Energy and Rates of chemical reactions
vocabulary
1) Exothermic Reaction: a chemical reaction in which heat is released to the surroundings
2) Endothermic Reaction: a chemical reaction that requires heat
3) Law of Conservation of Mass: the law that states that energy cannot be created or destroyed but can be changed from one form to another
4) Activation Energy: the minimum amount of energy required to begin a chemical reaction
5) Inhibitor: a substance that slows down or stops a chemical reaction
6) Catalyst: a substance that changes the rate of a chemical reaction without being used up or changed very much
2) Endothermic Reaction: a chemical reaction that requires heat
3) Law of Conservation of Mass: the law that states that energy cannot be created or destroyed but can be changed from one form to another
4) Activation Energy: the minimum amount of energy required to begin a chemical reaction
5) Inhibitor: a substance that slows down or stops a chemical reaction
6) Catalyst: a substance that changes the rate of a chemical reaction without being used up or changed very much
Section Summary
This section was about energy and rates of chemical reactions. First, are reactions and energy. There are two types of reactions, exothermic reactions (vocabulary word 1) and endothermic reactions (vocabulary word 2). In an exothermic reaction energy is given off (forms include light energy, electrical energy, or light/thermal energy. Exo- means "go out" or "exit". Thermic means "heat" or "energy". Next, were endothermic reactions wich are reactions in which energy is absorbed. Endo- means "go in" or "inside". The energy taken in is often written as a reactant in a chemical equation. Photosynthesis is an example of a endothermic reaction. While, these reactions take place the law of conservation of energy is displayed, which states that energy can never be created or destroyed.
Next, were rates of reactions. The speed at which new particles form is the rate of reaction. The smallest boost of energy needed to start a chemical reaction is called activation energy. A good example of this would be a spacecraft taking off. It takes a large amount of activation energy to take off at first, but after the initial take-off forward motion requires less energy. Activation energy can come from various sources but the most common source is friction.
Lastly, are factors that effect rates of reactions. The first of these factors is temperature. A higher temperature causes a faster rate of reaction because the rapid movement causes particles to collide more often with each other (with high energy). The next of these factors is concentration. Concentration is a measure of the amount of one substance dissolved in another substance. The greater the concentration becomes, the more particles are located in a given volume. This then causes an increased rate of reaction. Up next is surface area, which is the amount of exposed surface of a substance. The greater the surface area, the great chance there is of a reaction with other particles. Now are inhibitors, which is simply a substance that slows or stops a chemical reaction. Inhibitors are helpful in many ways. Preservatives are an example of inhibitors. The last factor is a catalyst. A catalyst is a substance that speeds up a reaction without being permanently changed (which is why it is not a reactant). Enzymes that speed up reactins in your body are an example of a catalyst. The pictures below may improve your understanding of activation energy (endothermic & exothermic).
Next, were rates of reactions. The speed at which new particles form is the rate of reaction. The smallest boost of energy needed to start a chemical reaction is called activation energy. A good example of this would be a spacecraft taking off. It takes a large amount of activation energy to take off at first, but after the initial take-off forward motion requires less energy. Activation energy can come from various sources but the most common source is friction.
Lastly, are factors that effect rates of reactions. The first of these factors is temperature. A higher temperature causes a faster rate of reaction because the rapid movement causes particles to collide more often with each other (with high energy). The next of these factors is concentration. Concentration is a measure of the amount of one substance dissolved in another substance. The greater the concentration becomes, the more particles are located in a given volume. This then causes an increased rate of reaction. Up next is surface area, which is the amount of exposed surface of a substance. The greater the surface area, the great chance there is of a reaction with other particles. Now are inhibitors, which is simply a substance that slows or stops a chemical reaction. Inhibitors are helpful in many ways. Preservatives are an example of inhibitors. The last factor is a catalyst. A catalyst is a substance that speeds up a reaction without being permanently changed (which is why it is not a reactant). Enzymes that speed up reactins in your body are an example of a catalyst. The pictures below may improve your understanding of activation energy (endothermic & exothermic).