2. Chemistry 2 Module 4 Readiness Standards

3. Atoms Protons, Neutrons, and Electrons What do you need to know? Atoms are in all matter. Atoms are smaller than cells. Atoms are not living. Protons are located in the nucleus and are positively charged. (+) Neutrons are found in the nucleus and have no charge. (o) Electrons are found in the electron cloud outside of the nucleus and are negatively charged. (-) Readiness

4. The Atom What atom is this? Can you identify the protons, neutrons, and electrons? Readiness

5. Atoms and Mass The mass of protons and neutrons are much larger when compared to the mass of the electrons. The total mass of the atom can be calculated by adding the protons and neutrons only. Because electrons are so small, their mass do not contribute significantly to the mass of the atom. Readiness Protons + Neutrons Electrons

6. Protons and Valence Electrons The number of protons in an atom’s nucleus determines the identify of the atom. If an atom has 1 proton, then it is a hydrogen atom. The number of valence electrons, the electrons found at the outer level of the electron cloud, determines how the atom will react chemically with other atoms. Readiness

7. Protons = Identity Valence electrons = reactivity Readiness 7 protons = Nitrogen 5 Valence electrons = 5A = Group 15

8. Periodic Table Groups and Periods The periodic table is arranged left to right by the atomic number (number of protons in the atom of that element). The periodic table also is arranged in groups (families) that run up and down in columns of the periodic table. All the elements are in the same group because they have the same number of valence electrons in each of their atoms, thus they react similarly to other atoms. The table is also arranged in rows called periods. Readiness

9. Groups and Periods Readiness

10. Chemical Formulas Chemical formulas, also called molecular formulas, are used to represent the chemical make-up of a particular molecule. Ex: H 2 O A subscript (2 as seen above) is used to show the number of Hydrogen atoms. So, in 1 molecule of water there are 2 hydrogen atoms and 1 oxygen atom. Readiness

11. Common Chemical Formulas How many atoms are there of each element? NaHCO 3 C 6 H 12 O 6 (Glucose) CuSO 4 (Copper sulfate) Readiness

12. Evidence of Chemical Reactions, New Substances Evidence of a chemical reaction includes the production of a gas, bubbling, a change in temperature, the production of a precipitate, or a color change. Color change can be misleading. If you mix purple Kool-aid powder with water and the water turns purple a chemical reaction DOES NOT take place. If two clear liquids combine to form a pink substance (precipitate) then a chemical reaction does take place. Readiness

13. Evidence of a new substance Precipitate Temperature Change Gas produced (bubbles) Readiness Color change- copper turns green when it oxides

14. Evidence that a New Substance forms from a chemical reaction Readiness