Introduction to Matter

Thought of the day You have mass, you take up space, You Matter!

What Is An Atom? An atom is the smallest unit of an element that maintains the properties of that element.

Parts of an Atom The atom has 4 main parts.

The Nucleus The nucleus is the center of the cell. Positively charged. Contains most of the atom’s mass.

Protons A subatomic particle found in the nucleus. Positively charged. Has a mass of 1.7x grams SI unit is 1 amu (atomic mass unit)

Neutrons A subatomic particle found in the nucleus. Have no charge. Mass is a little bigger than a proton. The mass of a neutron is still considered to be 1 amu

Electrons A subatomic particle found in electron clouds outside the nucleus. Negatively charged. The size of the electron cloud determines the size of the atom.

Atomic Number The number of protons in the nucleus of an atom is the atomic number. All atoms of an element have the same atomic number. Example: every Hydrogen atom has only one proton in its nucleus, so hydrogen has an atomic number of 1

How Many Protons are in... The element Carbon (C) ? The element Phosphorous (P) ? The element Chlorine (Cl) ? Easy huh?

Atomic Mass The mass of an atom is expressed in atomic mass units (amu). The mass number is the amount of protons added to the number of neutrons.

Electromagnetic Force Opposites attract! Objects that have different charges (positive and negative) are held together by electromagnetic forces. Objects that have the same charge (negative- negative or positive- positive) will always repel each other.

Will these charges repel or attract? Repel Attract Repel

Activity Use what you have just learned about charges to complete the activity.

Checking for Understanding What are the 3 subatomic particles? Fill in the blank: ___________ Attract. What makes objects attract or repel each other?

Properties of Matter Matter is anything that takes up space and has a mass. The amount of space taken up by an object is known as the objects volume.

Physical Properties State of matter- solid, liquid, or gas Freezing/ boiling point Mass, density, volume Conductivity- how well heat can flow through it Texture- smooth, bumpy, rough, soft, etc. Viscosity- how well a liquid flows

Physical Properties cont. Luster- shiny or non shiny Color Solubility- how well it dissolves

Evidence of a physical change Is easily reversible No new substances are formed There is no change in the mass of the substances involved It does not involve any great heat changes (except the latent heat changes which occur during changes of state)

Chemical Properties Reactivity with oxygen Reactivity with an acid Reactivity with other elements Flammability- the ability to burn pH- acid or base Stability- stable or unstable

Evidence of a chemical change Change is irreversible Gas production Temperature change pH change Color change Precipitate formation

States of matter

There are 3 states of matter SolidsLiquidsGases

Solids Solids have a definite shape AND a definite volume Composed of tightly packed particles. A solid will retain its shape; the particles are not free to move around.

Solids cont.

Liquids Liquids have a definite volume but NO definite shape They take on the shape of the container they are in Liquid matter is made of more loosely packed particles. Particles can move around within a liquid, but they are packed densely enough that volume is maintained. volume

Liquids cont.

Gases Gases have NO definite volume and NO definite shape Gaseous matter is composed of particles packed so loosely that it has neither a defined shape nor a defined volume. A gas can be compressed.

Gases cont.

RATES OF REACTION

Objectives Understand what is meant by “rate of reaction” Understand why reactions take place Interpret graphs of reaction rates

Some chemical reactions happen quickly. Fireworks Fireworks Exploding gummy bears Exploding gummy bears

Some chemical reactions happen slowly Rotting Rotting Rusting Rusting

For two substances to react together, they have to bump into each other. We call this a collision

If there are many collisions, then the rate of reaction is fast If there are few collisions, the rate is slow

Activation Energy Not only do particles have to bump into each other, but they have to bump into each other with enough energy to cause a reaction. Not only do particles have to bump into each other, but they have to bump into each other with enough energy to cause a reaction.

This is called the activation energy Different reactions need different amounts of activation energy

Energy (kJ) REACTANTS PRODUCTS Activation Energy

We measure how fast a reaction is taking place by looking at HOW FAST SOMETHING IS USED UP (REACTANTS) or HOW FAST SOMETHING IS MADE (PRODUCTS).

GRAPHS Graphs can tell us lots about how fast a reaction is taking place. THE STEEPER THE CURVE, THE FASTER THE REACTION IS.

A SLOW RATE OF REACTION NOT A VERY STEEP SLOPE (GRADIENT)

A FAST RATE OF REACTION A VERY STEEP SLOPE (GRADIENT)

The rate of any reaction does not remain the same. Most reactions SLOW DOWN as the REACTANTS are used up. Volume of gas Time 1 2 3

1 – Rate is FAST because there are lots of reactants available. 2 – Rate SLOWS DOWN as the reactants are used up 3 – Reaction STOPS because all the reactants have been used up.

Temperature vs. Energy Temperature is defined as the measure of the average speed of atoms and molecules The higher the temperature, the faster these particles of matter move

Endothermic vs. Exothermic Endothermic reactions- energy (heat) is being absorbed. (Feels colder) Exothermic reactions- Energy (heat) is being released. (Feels warmer)