CHAPTER 1: INTRODUCTION TO MATTER

DESCRIBING MATTER MATTER: It’s anything that has mass and takes up space. CHEMISTRY: the study of the properties of matter and how matter changes SUBSTANCE: It’s a single kind of matter that is pure. It has always a specific makeup

Every form of matter has two kinds of properties: physical and chemical.

PHYSICAL PROPERTIES: characteristic of a pure substance that can be observed without changing it into another substance. CHEMICAL PROPERTIES: characteristic of a pure substance that describes its ability to change into different substances.

ELEMENT: It is a Pure substance that cannot be broken down into any other by physical or chemical means. Simplest substance.

ATOM: basic particle from which all elements are made ATOM: basic particle from which all elements are made. Element’s properties differ due to the difference in the atoms.

CHEMICAL BOND: force of attraction between two atoms. MOLECULES: Combination of atoms into larger particles.

COMPOUND: pure substance made of two or more elements chemically combined in a set ratio. They are represented by a chemical formula. Ex: H2O, CO2, C6H12O6… When elements are chemically combined, they form compounds having properties that are different from those of the uncombined elements.

MIXTURES: It’s made of two or more substances (elements, compounds of both) Each substance in a mixture keeps its individual properties. The parts of a mixture are not combined in a set ratio

Heterogeneous Mixtures: you can see the different parts Homogeneous Mixtures: you can´t see the different parts Liquids: solution (sea water) Solids: alloy of metals Gases: Air

Which property do scientists prefer to describe matter? 2. MEASURING MATTER WEIGHT: it is a measure of the force of gravity on you. It is a force. MASS: it is the measurement of the amount of matter in the object. Unit (SI): kilogram- kg 1kg= 1000 g (grams) Which property do scientists prefer to describe matter? Weight or mass?

How can you measure the volume of an irregular object? VOLUME: the amount of space that matter occupies. Unit (SI): liter (l), mililiter (ml) and cubic centimeter (cm3) 1 liter= 1000 ml 1 ml= 1 cm3 Calculate volume: Volume= lenght x width x height Units= cm x cm x cm= cm3 Archimedes

DENSITY: relates the mass of a material in a given volume Units (SI)= g/cm3 Density of pure water is 1g/cm3.(4℃) Objects with greater density will sink, less will float.

Sample Problem A sample of liquid has a mass of 24g and a volume of 16ml. What is the density of the liquid? 1.5g/ml A piece of solid metal has a mass of 43.5g and a volume of 15cm3.What is the density of the metal? 2.9g/cm3

3. CHANGES IN MATTER A substance that undergoes a physical change is still the same substance after the change. Change in shape or form (ex: sugar) Common States of matter:(on the earth) Solid Liquid Gas

Other states (in the universe) Neutronium Supersolid Plasma

A change in matter that produces one or more new substances is a chemical change or a chemical reaction. New substances with new properties are produced. I.e.: combustion, oxidation…

Energy is the ability to do work or cause change. Law of Conservation of Mass or Matter (Lavoisier-1770): matter is not created or destroyed, It is only transformed. Energy is the ability to do work or cause change. Examples:bending a paper clip Ice changing to liquid water Candle wax burning, giving off energy

Temperature is a measure of the average energy of random motion of particles of matter. (I.e.: Air-conditioned: particules of gas in the warm outside air have greater energy of motion than the ones in the cool building.)

Thermal energy is the total energy of all the particles in an object Thermal energy is the total energy of all the particles in an object. Not the same than temperature. Always flow from warmer to cooler. Endothermic: energy is taken (ice melting) Exothermic: energy is given off or released (combustion)

4. ENERGY AND MATTER Forms of energy: Kinetic: the energy of matter in motion.

2. Potential: the energy an object has because of its position.

3. Chemical: energy stored in the chemical bonds between atoms.

4. Electromagnetic: it travels to the space as waves (ex:radio, microwave…)

Electrical: the energy of electrically charged particles moving from one place to another. Electrode: metal strips placed in solutions, attached to a wire, connected to a battery.

Transforming Energy During a chemical change, chemical energy may be changed to other forms of energy. Other forms of energy may also be changed to chemical energy.