Matter- is anything that has mass and takes up space. Chemistry- the study of matter and how matter changes. Physical Property- a characteristic of a substance that can be observed without changing the substance into another substance. EX: The temperature at which a solid melts is a physical property. (temperature, color, hardness, conducts heat, dissolves in water) Chemical Property- a characteristic of a substance that describes its ability to change into other substances. EX: When magnesium burns, it combines with oxygen in the air, forming a new substance called magnesium oxide. (burning, tarnishing, rusting) Physical Change- a change that alters the form or appearance of a substance but that does not make substance into another substance (change of state - solid, liquid, gas)(bending, crushing, breaking, cutting)(braiding hair) Chemical Change- occur when bonds break and new bonds form (burning of gasoline in a car engine) Chemical Reaction- a change in matter that produces one or more new substances and a change in energy Precipitate- A solid that forms from solution during a chemical reaction. Endothermic Reaction- a reaction in which energy is absorbed. (fry an egg) Exothermic Reaction- a reaction in which energy is released (fuel in an airplane - heat - force) Chemical Equation- a short easy way to show a chemical reaction, using symbols instead of words. Reactants- the substances you have in the beginning. Products- the new substance you have at the end. Conservation of Mass- during a chemical reaction, matter is not created or destroyed. All the atoms present at the start are present at the end. Open System- matter can enter from or escape to the surroundings (burning match) Closed System- matter is not allowed to enter or leave (chemical reaction inside a sealed plastic bag) Coefficient- a number placed in front of a chemical formula in an equation. Synthesis- when two or more elements or compounds combine to make a more complex substance. Decomposition- Breaks down compounds into simpler products. Replacement- When one element replaces another in a compound, or when two elements in different compounds trade places. Activation Energy- The minimum amount of energy needed to start a chemical reaction Catalyst- A material that increases the rate of a reaction by lowering the activation energy. Enzymes- Biological catalysts Inhibitor- A material used to decrease the rate of a reaction. Combustion- a rapid reaction between oxygen and a substance called a fuel.
Key Concepts: 1 - Observing Chemical Change
Matter can be described in terms of two kinds of properties- physical properties and chemical properties. Changes in matter can be described in terms of physical changes and chemical changes.
Chemical changes occur when bonds break and new bonds form.
Chemical reactions involve two main kinds of changes that you can observe- formation of new substances and changes in energy. (observe changes in the property - color change, solid may appears, a gas may be produced, moist bread)
Energy changes in chemical reactions
2 - Describing Chemical Reactions
Chemical equations use chemical formulas and other symbols instead of words to summarize a reaction.
The principle of conservation of mass states that, in a chemical reaction, the total mass of the reactants must equal the total mass of the products.
To describe a reaction accurately, a chemical equation must show the same number of each type of atom on both sides of the equation.
Many chemical reactions can be classified in one of three categories: synthesis, decomposition, or replacement.
3 - Controlling Cheming Reactions
All chemical reactions need a certain amount of activation energy to get started.
Chemists can control rates of reactions by changing factors such as surface area, temperature, and concentration, and by using substances called catalysts and inhibitors.
4 - Fire and Fire Safey
The following three things are necessary to start and maintain a fire: fuel, oxygen, and heat.
If you know how to prevent fires in you home and what to do if a fire starts, you are better prepared to take action.
Chemistry- the study of matter and how matter changes.
Physical Property- a characteristic of a substance that can be observed without changing the substance into another substance. EX: The temperature at which a solid melts is a physical property. (temperature, color, hardness, conducts heat, dissolves in water)
Chemical Property- a characteristic of a substance that describes its ability to change into other substances. EX: When magnesium burns, it combines with oxygen in the air, forming a new substance called magnesium oxide. (burning, tarnishing, rusting)
Physical Change- a change that alters the form or appearance of a substance but that does not make substance into another substance (change of state - solid, liquid, gas)(bending, crushing, breaking, cutting)(braiding hair)
Chemical Change- occur when bonds break and new bonds form (burning of gasoline in a car engine)
Chemical Reaction- a change in matter that produces one or more new substances and a change in energy
Precipitate- A solid that forms from solution during a chemical reaction.
Endothermic Reaction- a reaction in which energy is absorbed. (fry an egg)
Exothermic Reaction- a reaction in which energy is released (fuel in an airplane - heat - force)
Chemical Equation- a short easy way to show a chemical reaction, using symbols instead of words.
Reactants- the substances you have in the beginning.
Products- the new substance you have at the end.
Conservation of Mass- during a chemical reaction, matter is not created or destroyed. All the atoms present at the start are present at the end.
Open System- matter can enter from or escape to the surroundings (burning match)
Closed System- matter is not allowed to enter or leave (chemical reaction inside a sealed plastic bag)
Coefficient- a number placed in front of a chemical formula in an equation.
Synthesis- when two or more elements or compounds combine to make a more complex substance.
Decomposition- Breaks down compounds into simpler products.
Replacement- When one element replaces another in a compound, or when two elements in different compounds trade places.
Activation Energy- The minimum amount of energy needed to start a chemical reaction
Catalyst- A material that increases the rate of a reaction by lowering the activation energy.
Enzymes- Biological catalysts
Inhibitor- A material used to decrease the rate of a reaction.
Combustion- a rapid reaction between oxygen and a substance called a fuel.
Key Concepts:
1 - Observing Chemical Change
2 - Describing Chemical Reactions
- Chemical equations use chemical formulas and other symbols instead of words to summarize a reaction.
- The principle of conservation of mass states that, in a chemical reaction, the total mass of the reactants must equal the total mass of the products.
- To describe a reaction accurately, a chemical equation must show the same number of each type of atom on both sides of the equation.
- Many chemical reactions can be classified in one of three categories: synthesis, decomposition, or replacement.
3 - Controlling Cheming Reactions- All chemical reactions need a certain amount of activation energy to get started.
- Chemists can control rates of reactions by changing factors such as surface area, temperature, and concentration, and by using substances called catalysts and inhibitors.
4 - Fire and Fire Safey