1. Notes: A New Language9/25 Essential Question: What are elements and compounds, and how do we describe them in chemical formulae?

2. Element – any material that cannot be broken apart by chemical reactions. Element – any material that cannot be broken apart by chemical reactions. water is not an element - water is not an element - it can be split into the elements hydrogen and oxygen it can be split into the elements hydrogen and oxygen

3. Atom – the smallest possible piece of an element that still has the element’s properties Compound – a combination of different elements. carbon and oxygen make up carbon dioxide (CO 2 ) carbon and oxygen make up carbon dioxide (CO 2 )

4. Making Sense: Atomic Lego Element  the type of Lego piece Element  the type of Lego piece 1 x 1, 2 x 2, 2 x 6, wheel … 1 x 1, 2 x 2, 2 x 6, wheel … Atom  one Lego block Atom  one Lego block “Pure gold” would be millions of yellow 2x8 blocks put together – one element, many atoms. “Pure gold” would be millions of yellow 2x8 blocks put together – one element, many atoms.

5. Lego Model (2) Compound  Lego model of toy car Compound  Lego model of toy car Uses different kinds of Lego. Uses different kinds of Lego. 2x2, 2x8, wheels, wedges… 2x2, 2x8, wheels, wedges…

6. Lego Model Elements: # atoms Sq1 Di2 F2F2F2F2 Compound = Star Wars Star Wars tie fighter tie fighter Sq Di 2 F2F2F2F2

7. Warm-up Sort the following into elements and compounds: Sort the following into elements and compounds: USiAlF 3 SIH 2

8. Properties Elements and compounds have consistent properties that help us identify them. color, hardness, density… Copper turns things green or blue. Iron is magnetic.

9. Chemical symbols are 1 or 2 letter codes (abbreviations) that identify each element. The first letter is a capital letter. C = carbonCu = copper H = hydrogenHe = helium A Chemical formula tells what elements are in a compound … and their ratio. CH 4 = 1 Carbon, 4 Hydrogen AlPO 4 = 1 Aluminum, 1 Phosphorus, 4 Oxygen

10. (s) = solid (l) = liquid (g) = gas (aq) = aqueous … which means dissolved in water Phases in a formula are shown in parentheses:

11. Quizlet Imagine that you find a vial labeled “Sodium sulfate Na 2 SO 4 (aq).” 1. 1. What does the “aq” mean? 2. 2. Is this a compound or an element? 3. 3. How many elements are there? 4. 4. How many atoms are there?

12. Quizlet 2 Imagine that you find a vial labeled “Nitrogen N 2 (g).” 1. 1. What does the “g” mean? 2. 2. Is this a compound? 3. 3. How many elements are there? 4. 4. How many atoms are there?