1. Nature of Matter

2. Matter Anything that takes up space Has mass You are made up of matter…and so is everything around you

3. Looking more closely at matter… Atoms: basic building blocks of matter Atoms are made up of Subatomic particles: PROTONS NEUTRONS ELECTRONS

4. Subatomic particles Proton: +, nucleus Neutrons: neutral, nucleus Electrons: negative, cloud around nucleus; organization inside cloud – into shells

5. Atomic Rules The number of protons and electrons are usually equal in an atom So the positives and negatives balance out… So the overall charge of an atom is: 0

6. Elements Pure substance Made up of only one type of atom

8. Key elements for living things CARBON (C) HYDROGEN (H) OXYGEN (O) PHOSPHORUS (P) NITROGEN (N) SULFUR (S)

9. Atomic Number Number of protons in an atom – Carbon’s atomic number = 6 – So carbon has 6 protons And by default…since atoms are neutral, we can say: – Atomic number is also equal to the number of electrons

10. PRACTICE! Neon = atomic number is 10 – # protons? – # electrons? CHLORINE = atomic number is 17 – # protons? – # electrons?

11. Side Note If we change the atomic number, we change the element we are talking about…

12. What about the neutrons? Atoms of the same element can have different numbers of neutrons Isotopes: atoms of the same element that have different numbers of neutrons Atomic Number: sum of the protons and neutrons in the nucleus of an atom

13. So… To figure out the number of neutrons in an atom…you have to: Atomic mass – atomic number = # of neutrons Practice: carbon’s atomic number is 6, mass is 12

14. More practice Chlorine: atomic number = 17 atomic mass = 35

15. Compounds Substance formed by the chemical combination of two or more elements in definite proportions Example: WATER! Water is NOT an element! Made up of 2 elements!!

16. Activity! Let’s build some water!!!