1. INTRO TO CHEMISTRY Biology I

2. Matter occupies spacemass Anything that occupies space and has mass. Examples: Examples: 1.rock 2.wood 3.metal 4.air

3. Matter is divided into 3 states Solids have both a definite volume & definite shape (rock) Liquids have a definite volume but no definite shape; they can be poured (water) Gases do not have a definite volume or definite shape, but they take the volume & shape of their container

4. Matter consist of atoms, which are the smallest unit of matter that can’t be broken down. Most atoms consist of 3 particles: Electrons---Protons---Neutrons

5. Components of an Atom Component ChargeLocation 1.Protonpositive nucleus 2.Neutronneutral nucleus 3.Electronnegative around the nucleus

6. Atoms The simplest particle of an element that retains all the properties of that element Properties of atoms determine the structure and properties of the matter they compose Our understanding of the structure of atoms based on scientific models not observation

7. The Nucleus Central core Consists of positive charged protons and neutral neutrons Positively charged Contains most of the mass of the atom

8. The Protons All atoms of a given element have the same number of protons Number of protons called the atomic number Number of protons balanced by an equal number of negatively charged electrons

9. The Neutrons The number varies slightly among atoms of the same element

10. The Electrons Negatively charged high energy particles with little mass Travel at very high speeds at various distances (energy levels) from the nucleus

11. Chemical Elements Elements are pure substances which cannot be chemically broken down into simpler kinds of matter. Elements are pure substances which cannot be chemically broken down into simpler kinds of matter. More than 100 elements have been identified, but only about 30 are important in living things More than 100 elements have been identified, but only about 30 are important in living things All of the Elements are arranged on a chart known as the Periodic Table All of the Elements are arranged on a chart known as the Periodic Table Periodic charts tell the atomic number, atomic mass, & chemical symbol for every element Periodic charts tell the atomic number, atomic mass, & chemical symbol for every element Four elements, Carbon – C, Hydrogen – H, Oxygen – O, and Nitrogen – N make up almost 90% of the mass of living things Four elements, Carbon – C, Hydrogen – H, Oxygen – O, and Nitrogen – N make up almost 90% of the mass of living things

12. Chemical Elements cont.. Each element has an unique chemical symbol Consists of 1-2 letters First letter is always capitalized The number of protons in an atom is called the atomic number & determines which element it is. The number of protons & neutrons is called the atomic mass or mass #.

13. How do we find the #of neutrons? Atomic mass (# of neutrons & protons) - Atomic # (# of protons) = # of neutrons 10 12 835

14. ELECTRONS  The number of positively charged protons is balanced by an equal number of negatively charged electrons (e-).  Electrons at outer levels have more energy than those in inner levels.  Each level or shell can only hold a certain # of e-  The first level, nearest the nucleus can only hold two electrons, the second and other outer levels can hold up to eight electrons each.  A stable atom is an atom that has a full outer level

15. Electrons in the same energy level are approximately the same distance from the nucleus Outer energy levels have more energy than inner levels Each level holds only a certain number of electrons

16. A T O M S

17. Compound two or more elements Substance containing two or more elements. Example:C 6 H 12 O 6 (glucose - sugar) Example:C 6 H 12 O 6 (glucose - sugar) 6 - carbons 6 - carbons 12 - hydrogen 6 - oxygen 6 - oxygen

18. Question: Answer the following questions about C 6 H 12 O 6 Answer the following questions about C 6 H 12 O 6 elements 1.How many elements are involved? atoms 2.How many atoms are involved?

19. Answer: 1Elements- 3 (C, H, O) 1. Elements - 3 (C, H, O) 2. Atoms - 24

20. Atom smallest unit of matter element The smallest unit of matter that still retains the properties of an element.

21. Carbon - Atom Protons - 6 Neutrons- 6 Electrons- 6

22. Atomic Number Equalsnumber of protons Equals the number of protons within the nucleus of an element. Examples: Examples: Hydrogen (H)- 1 Sodium (Na)- 11 Carbon (C)- 6 Oxygen (O)- 8 Gold (Au)- 79

23. Atomic Mass Equalsprotons + neutrons Equals the number of protons + neutrons. Examples: Examples: Hydrogen (H)- 1.0079 Sodium (Na)- 23 Carbon (C)- 12 Oxygen (O)- 16 Gold (Au)- 197

24. Charge of an Element Question:protonselectrons Question:protons = electrons Answer:neutral Answer:charge is neutral Question:protons electrons Question:protons  electrons Answer:either negative or positive Answer:the charge is either negative or positive

25. Isotope Atoms neutrons Atoms of elements with different number of neutrons. Examples: Examples: carbon - 12 carbon - 13 carbon - 14

26. Isotopes of Carbon Nucleus 12 C 13 C 14 C protons666 neutrons678 electrons666

27. Electrons nucleus orbit around the nucleus 2 electrons first bonding orbital - 2 electrons maximum 8 electrons all other bonding orbitals - maximum 8 electrons energy levels orbitals have certain energy levels orbitals farther from the nucleus have the highest energy level.

28. Sodium and Chlorine – Electrons Bonding Orbitals Na Cl

29. Chemical Bonding Threebondsdifferent strengths Three types of bonds with different strengths: covalent > ionic > hydrogen

30. Covalent Bonds strongest bond strongest bond shareone or more pairs two elements share one or more pairs of outer electrons singledouble bonds single and double bonds Examples: Examples: 1.H 2 O(water - polar molecule) 2.CH 4 (methane) 3.O 2 (dioxide) O-O- H+H+ H+H+ O=O H-C-HH-C-H H H

31. Ion electric charge atom or molecule with an electric charge. gain or loss of one or more electrons resulting from a gain or loss of one or more electrons. Examples: Examples: Sodium ion (Na + ) Chloride ion (Cl - )

32. Ionic Bonds second strongest bond second strongest bond two ions with opposite charges attract to each other. two ions with opposite charges attract to each other. Examples: Examples: salts (NaCl) acidsbases

33. Ionic Bond Example:salt (NaCl) Example:salt (NaCl) Cl Na

34. Hydrogen Bonding weakest of the three bonds. weakest of the three bonds. Most important and common of all bonds. Most important and common of all bonds. Partially positive hydrogen partially negative atom (O or N). Partially positive hydrogen atom of one molecule is attracted to the partially negative atom of another molecule (O or N). Example:H 2 O Example:H 2 O O-O- O-O- H+H+ H+H+ H+H+ H+H+ H+H+ O-O- H+H+ H+H+ O-O- H+H+ hydrogen bonds