1. Chemistry of Life and Models

2. Chemistry An element is An atom A pure chemical substance consisting of one type of atom The smallest component of an element having the same chemical properties of that element

3. The Chemistry of Life Everything is made of elements ____ elements occur naturally 92 Natural elements in living things Four elements make up 96% of the mass of a human _________________ CarbonC HydrogenH OxygenO NitrogenN Elementsymbol

4. The Chemistry of Life Six elements that are the main components of living matter are ______, ______, _______, ______, _________, __________ Trace elements- elements present in living things in small amounts which controls cell ________ OxygenCarbon HydrogenNitrogen Calcium-CaPhosphorus-P metabolism Element usedWhy it is used Mammals use Plants use iodine For growth, development & chemical activity magnesium To form chlorophyll in chloroplasts Fluorine To help teeth resist decay

5. Atoms: The Building Blocks of Elements Both living an nonliving things are made of atoms An atom is the smallest particle of an element that has its characteristics Structure of an atom Subatomic particleSymbolChargeLocation proton neutron electron p + nucleus n0 e - energy levels

6. electron neutron proton nucleus Periodic Table… Is a chart to organize elements Has more than ______ elements 100 Model of an atom Which element is shown in this model? Helium

7. 1 1.0079 H hydrogen Example: Atomic number Atomic mass Symbol Element name

8. Bohr Model 1.Write the number of p’s and n’s in the nucleus 2.Write the number of electrons in each energy level to complete the model a.1 st energy level = _____ electrons b.2 nd energy level = _____ electrons c.3 rd energy level = _____ electrons 8 8 2

9. Example: Magnesium p = n = e = 12 p= n= 12 Subtract the number of p’s from the atomic mass E’s in the outermost energy level are called valence electrons How many valence e’s does magnesium have? 2 Activity- click here for period table

10. Atomic number- Atomic number- number of protons Atomic mass- Atomic mass- sum of protons plus neutrons