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Chemistry: The Study of Matter

Chemistry: The Study of Matter. Matter. Anything that has mass or takes up volume Cannot be created nor destroyed Exists in four states: Solid Liquid Gas Plasma. Classification of Matter. All Matter is made up of ATOMS. Atoms

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Chemistry: The Study of Matter

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  1. Chemistry: The Study of Matter

  2. Matter • Anything that has mass or takes up volume • Cannot be created nor destroyed • Exists in four states: • Solid • Liquid • Gas • Plasma

  3. Classification of Matter

  4. All Matter is made up of ATOMS • Atoms • An atom is the smallest particle of an element that still has the properties of that element • “ There are possibly more atoms within this single grain of sand than there are grains of sand in this entire beach”

  5. Atoms are made up of subatomic particles ELECTRONS (-) - Particles outside the nucleus with a negative charge! PROTONS (+) - Particles in nucleus with a positive charge! NEUTRONS - Particles in nucleus with no charge!!!!! Protons & neutrons are held tightly at the centre of the atom in a small region called the NUCLEUS

  6. The NEUTRAL ATOM….. Neutral atom has the samenumber of protons and electrons Nuclear Charge - Equal to the number of proton charge Most of an atom’s atomic mass comes from the nucleus

  7. PROTONS & ELECTRONS in an ATOM ATOMIC NUMBER = # OF PROTONS = # OF ELECTRONS Not important yet!!! ATOMIC NUMBER How many protons are in this sodium atom? How many electrons are in this sodium atom? 11 11

  8. Number of NEUTRONS in an ATOM Rounded Atomic Mass Number of NEUTRONS — Number of Protons = What is the number of protons? What is the number of electrons? What is the number of neutrons? 15 ATOMIC NUMBER 15 ATOMIC MASS 31-15 = 16

  9. Atomic number = # of protons = # of electrons • Number of neutrons = Atomic mass - # of protons • Electrical charge of an atom is neutral 1 1 1 0 1 0

  10. Bohr Diagrams for ATOMS • Bohr diagram shows how many electrons are in each electron shell around an atom • The outer most shell is called the valence shell ELECTRON SHELLS K VALENCE SHELL!!!

  11. Bohr Diagram for ATOMS To draw Bohr Diagrams: • Determine the number of electrons • Write the element symbol • Determine number of shells • Fill the shells according to the following: • The first shell holds only 2 ELECTRONS • The second shell holds 8 ELECTRONS • The third shell holds 8 ELECTRONS

  12. Bohr Models for ATOMS 2 2 2 0 0 1. Determine # of electrons 2. Write the elemental symbol He 3. Determine number of shells 4. Fill electrons according to 2, 8, 8 rule

  13. Bohr Models for ATOMS 6 6 2 4 0 1. Determine # of electrons 2. Write the elemental symbol C 3. Determine # of shells 4. Fill shells with electrons with the 2, 8, 8 rule

  14. Bohr Models for ATOMS 17 17 2 8 7 1. Determine # of electrons 2. Write the elemental symbol Cl 3. Determine # of shells 4. Fill shells with electrons

  15. Phosphorus • Sodium

  16. ORGANIZATION OF PERIODIC TABLE The periodic table is organized: - according to the atomic number - according to electron patterns - into rows called periods - into columns called groups / family - metals on the left - transition metals in the middle - non-metals on the right - Metalloids form the staircase

  17. Columns are called GROUPS Rows are called PERIODS

  18. PERIODIC TABLE ORGANIZED ACCORDING TO ELECTRONS 1 valence e- Full valence e- The Group/ Family (column) tells you number of valence electrons The Period (row) tells you number of Shells 2 valence e- 7 valence e- 3 valence e- 4 valence e- 5 valence e- 6 valence e- One shell Two shells Three shells

  19. GOAL of elements at ATOMIC LEVEL TO HAVE A FULL VALENCE SHELL!!!!!!!!!!!!! The closer they are to the full valence shell, the more desperate they get!! Therefore, more reactive!

  20. Group 1 = ALKALI METALS • Desperate to give away 1 electron!!!! • VERY REACTIVE!!!!

  21. Group 1 = ALKALI METALS

  22. Group 2 : Alkali Earth Metals • Not as desperate.... Not as reactive • Wants to give away 2 electrons

  23. Group 17 : Halogens • Very reactive!!!!! • Wants to TAKE 1 more electron!!! • Reacts with alkali metals

  24. Group 18: Noble Gases • They have a FULL valence shell • They’re happy and very STABLE • Not reactive

  25. IONS • When atoms gain or lose electrons they become electrically charged and form IONS 1- F F • Positive Ion is called CATION • Negative Ion is called ANION

  26. IONS ELECTRICAL CHARGE • If Lithium has 3 protons..... • And it usually has 3 electrons...... • How many electrons does it have? • BUT IT LOSES AN ELECTRON • 2!!! 3 protons = + 3 2 electrons = -2 ELECTRICAL CHARGE = +1

  27. ION’S ELECTRICAL CHARGE • If Fluorine has 9 protons..... • And it usually has 9 electrons...... • How many electrons does it have? • BUT IT GAINED AN ELECTRON • 10!!!! 9 protons = + 9 10 electrons = -10 ELECTRICAL CHARGE = -1

  28. IONS ATOMIC NUMBER = Number of Electrons IN AN ATOM This is very important for IONS, it is the IONIC CHARGE Positive charge = lost electron Negative charge = gained electron Atomic mass: Atomic mass – # of protons= number of neutrons

  29. Remember!!! • Positive Charge means an electron was LOST • Negative charge means an electron was GAINED

  30. Bohr Models for IONS 2 8 8 17 17 1 - Gain 1 18 1- 1. Determine atomic # & number of electrons in atom 2. Determine electrical charge Cl 3. Did you gain or lose electron? 4. Draw Bohr Model 5. Add ionic charge + 17 – 18 = -1

  31. Bohr Models for IONS 2 0 0 3 3 1 + Lose 1 2 1+ Li Li + 3 – 2 = + 1

  32. Forming Compounds • When 2 atoms get close together, their VALENCE ELECTRONS INTERACT • If atoms can form a stable bond, a compound is formed • Remember, the goal is to GET A FULL VALENCE SHELL

  33. Forming Compounds • There are 2 types of compounds • IONIC COMPOUND • COVALENT COMPOUND

  34. IONIC COMPOUNDS • Ionic compounds form ionic bonds • Inionic bonding, electrons are transferred • An ionic compound consists of metal and non-metals • The metals donates/loses electrons • The non-metals gains/ accepts electrons • After the electrons are transferred, the ions are attracted to each other and form a bond

  35. Example 1: Ionic Bonding

  36. Example 2: Ionic Bonding • You have lithium and oxygen O Li • How many Lithiums do you need to make Oxygen Happy? • 2!!!

  37. + Electrons are transferred from the positive ions to negative ions oxygen lithium Li+ O2- Li+ lithium oxide, Li2O

  38. COVALENT COMPOUNDS • Covalent compounds form covalent bonds • In a covalent bond, atoms SHARE ELECTRONS between non-metals • This results in their shells overlapping + Hydrogen fluoride electrons are shared hydrogen fluorine

  39. It is the Valence shells that determine reactivity. Lets just look at the valence shells!

  40. Electron pairs involved in a covalent bond are called BONDING PAIRS Electron pairs NOT used in bonding are called LONE PAIRS

  41. Diatomic Molecules • Molecules where 2 of the same atoms are covalently bonded are called diatomic molecules. • The following are diatomic molecules I2 H2 N2 Br2 O2 Cl2 F2 • IHave No Bright Or Clever Friends

  42. LEWIS DIAGRAMS • Lewis diagrams only show the valence electronsand chemicalsymbol to representchemicalbonding • Onlyneed to draw valence electrons!

  43. Lewis Diagrams for ATOMS • Before • After

  44. Lewis Diagrams for IONS 17 7 1 - Gain 1 8 1- 1. Determine Group Number 2. Determine valence electrons in ATOM and electrical charge Cl 3. Gain or lose e- 4. Determine number of valence e- in an ION 1- 5. Add ionic charge

  45. Lewis Diagrams for IONS 1 1 1 + Lose 1 0 1- Na Na

  46. Lewis Diagram for Compounds • Dots show the pairs of electrons in the valence shell • Linesrepresentbonds or e-shared • GOAL OF ATOMS: gain a FULL valence shell Lone Pairs!!! F H F H Bonding Pairs!!!!!!

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