1. A MATTER OF FACT Introduction to Elements, Atoms, and the Periodic Table

2. WHY ISN’T IT A GOOD IDEA TO CLASSIFY MATTER BY ITS PHASES?  Because one kind of substance can exist in more than one phase (such as H 2 0 can be ice, water, or steam) and matter changes phases rather easily.

3. WHY ISN’T MATTER CLASSIFIED ACCORDING TO ITS PHYSICAL CHARACTERISTICS, SUCH AS COLOR?  Scientists would not find it very useful to group sunflowers, gold, and the sun together.

4. ELEMENTS, COMPOUNDS, & MIXTURES  Scientists like to classify things.  One way that scientists classify matter is by its composition (what it’s made of)  All matter can be classified as one of three categories: elements elements compounds compounds mixtures mixtures

5. ELEMENTS  Elements are the simplest pure substances.  An element cannot be broken down or separated into simpler substances by physical or chemical means.  Elements are the building blocks of all materials.  About one hundred elements can combine in different ways to form millions and millions of different substances!

6. ELEMENTS AND ATOMS  Elements are made of particles.  Elements are pure substances.  All of the particles that make up an element are exactly alike.  The smallest particle into which an element can be divided and still be the same substance is called an… Atom

7. PARTS OF THE ATOM  Atoms are made of three different types of particles:  Proton – Positively charged (+)  Neutron – No charge (neutral)  Electron – Negatively charged (-)  Nucleus – Center of the atom  Made of protons and neutrons  Electrons are constantly moving around the nucleus.

8. PARTS OF THE ATOM

9. ELEMENTS AND THEIR SYMBOLS  In 1813, a system of symbols representing the elements was introduced.  Each symbol consists of one or two letters.  Two letters are needed for a chemical symbol when the first letter of that element’s name has already been used.

10. COMMON ELEMENTS AluminumAl BromineBr CalciumCa CarbonC GoldAu HeliumHe HydrogenH NitrogenN

11. PERIODIC TABLE

12. CLASSES OF ELEMENTS  Metals  Most of the elements on the periodic table are metals.  Metals tend to be solids that are shiny, malleable, ductile, and good conductors of electricity.  Nonmetals  More than half of the nonmetals are gases.  Nonmetals typically are not shiny, not malleable, not ductile, and are poor conductors of electricity.  Metalloids  Metalloids are also known as semiconductors.  Metalloids have some properties of metals and some of nonmetals.