1. Elements, Compounds, & Chemical Names

2. Elements A pure substance that cannot be separated into a simpler substance by physical or chemical means. Elements are the building materials of all matter.

3. -Of the 118 known elements, only 92 are known to occur naturally in nature.

4. Compounds Pure substance composed of two or more different elements joined by chemical bonds. Made of elements in a specific ratio that always has the same chemical formula Can only be separated by chemical means, not physically

5. *Compounds can be very different in appearance and behavior from the elements that they are composed of. Ex: Sodium (Na) combined with chlorine (Cl) makes the compound sodium chloride (NaCl) Reaction of pure sodium with water…… a very violent reaction!

6. Mixtures A combination of two or more pure substances that are not chemically combined. substances held together by physical forces, not chemical Each item retains its properties in the mixture They can be separated physically

7. Element, Compound, or Mixture? Jelly Beans

8. Element, Compound, or Mixture? Table Sugar

9. Element, Compound, or Mixture? Diamond

10. Aqueous Copper Sulfate

11. Chemical Names & Symbols Elements combine in specific ratios to form compounds Symbol for sulfurSymbol for oxygen Subscript for oxygenSymbol for copper

12. Names and Symbols (cont.) The first letter of an element’s symbol is always uppercase, and if there is a second letter it is always lowercase. Compounds are represented by chemical formulas. Chemical formula: A combination of symbols and subscripts that indicates the number and types of elements in a compound.

13. Examples of Element Symbols

14. Examples of Chemical Formulas for 2 different compounds. Copper Sulfate, CuSO 4 (s)Copper sulfide, CuS(s)

15. Copper carbonate hydroxide Cu 2 (CO 3 )(OH) 2 (s) Substances come in different physical forms, called phases. Phase: The physical form a substance is in, such as solid, liquid, or gas. Phase is greatly influenced by temperature. Aqueous: A substance is aqueous when it is dissolved in water.

16. The symbols (s), (l), (g), and (aq) indicate the physical form or phase of a substance and whether it is dissolved in water.