Chemistry of Life

1. Chemistry of Life Inorganic Chemistry

2. What is an element? • A Pure substance that contains on one type of atom. • There are 92 naturally occurring elements. • They are put together in the form of “The Periodic Table of the Elements”

3. 96% of the mass of a human is made up of the following four elements: • Carbon (C) • Hydrogen (H) • Oxygen (O) • Nitrogen (N) • The one or two letter abbreviation is called the chemical symbol. • Sodium (Na) • Chlorine (Cl)

4. What is an atom? • An atom is the basic unit of matter. • It includes a central nucleus which includes protons and neutrons. • Protons have a positive (+) charge and neutrons have a neutral charge.

5. An electron cloud surrounds the nucleus. It is comprised of energy levels that contain electrons. • Electrons have a negative (-) charge.

6. Each energy level can only hold a certain amount of electrons. • 1st : 2 electrons • 2nd : 8 electrons • 3rd : 8 electrons

7. Atomic number: # of protons • Mass Number: # of protons + # of neutrons • Symbol: one or two letters representing the element

8. Isotope- Same element but with a different number of neutrons • Protons stay the same, neutrons change. This means the mass number changes.

9. Atoms of 2 or more different elements chemically joined together form a compound. • Examples of compounds: • Water (H2O) – hydrogen and oxygen bonded together • Table salt (NaCl) – Sodium and chloride bonded together

10. Covalent bonds share electrons. • Example of covalent bonds is water (H2O). • Ionic bonds transfer electrons • Example of ionic bonds: table salt (NaCl).

11. Molecule • Smallest particle of a substance; it retains its properties through composed of one or more atoms positively (+) or negatively (-) charged. • Ion: a charged particle (pos or neg)

12. Mixture: substances or combined, but each keeps its own properties. • Example: saltwater, big mac • Solution: mixture of one or more substances (one being dissolved and the other does the dissolving) • Solute: substance being dissolved in a solution • Solvent: substance doing the dissolving in a solution

13. Example of parts of a solution: • Lemonade=solution • Solvent=water • Solute=sugar/lemon juice

14. pH • A measure of how acidic or basic a solution is. • 1-6 Acidic • 7 neutral • 8-14 Basic

15. Acid • Below 7, More H+ than OH- • Ex: Lemon juice, milk, HCl

16. Base • Above 7; less H+ than OH- • Ex: ammonia, drain – o , eggs, soap

17. Neutral • pH = 7; equal amount of H+ and OH- • Ex: pure water.

18. pH scale • Ranges from 0-14 • 0=strongest acid • 14=strongest base

19. Polar molecule • Atoms in covalent bond that do not share electrons equally (has positive and negative ends) • Typically disolves in H2O. • Ex: Water, H2O

20. Hydrogen bond • Weak bond created by a hydrogen atom attracted to oppositely charged atoms • Ex: Water, 2 hydrogens (+) + 1 oxygen (-) = H2O

21. Non-polar molecule • Electrons are equally shared by atoms • Ex: O2, H2, CH4 (methane)

22. Characteristics of Water: • Water is polar • Water resists temperature changes • Water expands when it freezes • Water is cohesive – it sticks to itself • Water is adhesive – it sticks to other stuff • Water has surface tension – Ex: a bug walks on water.

23. Surface Tension • Water’s ability to stick to itself. • This causes some insects to walk on water, causes rain to form droplets and small objects to float on water. • It is a cohesive force between the molecules of water.

24. Let’s draw an atom… • Remember atoms include a nucleus with protons and neutrons. • An electron cloud surrounds the nucleus. • Using three colors, draw this atom in the empty space in your notes.