4.1: Atomic Theory & BONDING

1. 4.1: Atomic Theory & BONDING

2. 4.1: Learning Outcomes • 1. Demonstrate knowledge of the three subatomic particles, their properties, and their location within the atom. • 2. Define and give examples of ionic bonding (e.g., metal and non‐metal) and covalent bonding (e.g., two non‐metals, diatomic elements). • 3. With reference to elements 1 to 20 on the periodic table, draw and interpret Bohr models, including protons, neutrons, and electrons, of: • atoms (neutral) • ions (charged) • molecules ‐ covalent bonding (e.g., O2, CH4) • ionic compounds (e.g., CaCl2)

3. 4.1: Learning Outcomes 4. Identify valence electrons using the periodic table. 5. Distinguish between paired and unpaired electrons for a single atom. 6. Draw and interpret Lewis diagrams showing single bonds for simple ionic compounds and covalent molecules (e.g., NaCl, MgO, BaBr2, H2O, CH4, NH3). 7. Distinguish between lone pairs and bonding pairs of electrons in molecules.

4. 4.1: VOCABULARY Alkali earth metals Alkali metals Anions Atomic # Atomic number Atomic Theory Atoms Bohr diagram Cations Chemical Change Chemical reaction Compound Covalent bonding Covalent Compound Electrons Element Family/Group Halogens Ionic bonding Ionic compounds Ions Lewis Diagram Matter Metal Metalloids Mixture Molecule Neutron Noble gases Non-Metal Nucleus Period Proton Pure Substance Stable outer shell Subatomic particle Transition metals Valence electrons

5. Chemistry is the study of... MATTER!!!

6. What is matter? Anything with mass and volume! Found in 3 phases: liquid, solid, gas Can't be created or destroyed, it only changes form

7. MATTER Mixtures Pure Substances Compounds Solutions Elements Mechanical Suspensions

8. CHANGES IN MATTER PHYSICAL CHANGE CHEMICAL CHANGE No new substances produced New substances produced Very hard to reverse Only a change in state or appearance = CHEMICAL REACTION

9. PHYSICAL CHANGE

10. CHEMICAL CHANGE

11. ATOMS • An atom is the smallest particle of an element that still has the properties of that element • 50 million atoms, lined up end to end = 1 cm • An atom = proton(s) + neutron(s) + electron(s) See pages 168 - 169 (c) McGraw Hill Ryerson 2007

12. ATOMS FORM COMPOUNDS • Atoms join together to form compounds. • A compound is a pure substance that is composed of two or more atoms combined in a specific way. • Oxygen and hydrogen are atoms/elements; H2O is a compound. See pages 168 - 169 (c) McGraw Hill Ryerson 2007

13. ATOMS FORM COMPOUNDS

14. CHEMICAL CHANGE A chemical change occurs when the arrangement of atoms in compounds changes to form new compounds. See pages 168 - 169 (c) McGraw Hill Ryerson 2007

15. CHEMICAL CHANGE Sodium Na (solid) Chlorine Cl (gas) Salt NaCl

16. ATOMIC THEORY • Atoms are made up of smaller particles called subatomic particles. See page 170 (c) McGraw Hill Ryerson 2007

17. ATOMIC THEORY If the proton & neutron were enlarged, and each had the mass of a hippopotamus, the electron, enlarged to the same scale, would have less mass than an owl.

18. ATOMIC THEORY • The nucleus is at the centre of an atom. • The nucleus is composed of -positive protons -neutral neutrons • Electrons exist in the space surrounding the nucleus. See page 170 (c) McGraw Hill Ryerson 2007

19. ATOMIC THEORY • # of protons = # of electrons in every atom • Nuclear charge = charge on the nucleus = # of protons • Nuclear charge = Atomic number • Atomic number = # of protons = # of electrons See page 170 (c) McGraw Hill Ryerson 2007

20. INCREASING REACTIVITY

21. INCREASING REACTIVITY The Periodic Table • Where are the following? • Atomic number See page 172 (c) McGraw Hill Ryerson 2007

22. Organization of the Periodic Table • In the periodic table elements are listed in order by their atomic number. • Metals are on the left • The transition metals range from group 3 -12 • Non-metals are on the right • Metalloids form a “staircase” toward the right side. See page 171 (c) McGraw Hill Ryerson 2007

23. Metals (left of zig zag line) Physical Properties of Metals: Shiny, good conductors of heat and electricity, ductile (make wires) and malleable (thin sheets). Easily lose electrons. Like to join with non-metals. Corrode (tarnish/rust). Nonmetals (right of zig zag line) Physical Properties of Nonmetals: dull appearance, poor conductor, brittle (breaks easily), not ductile or malleable. Easily gain electrons. Like to join with metals, but will bond to other non-metals. Metalloids (on both sides of zigzag line) Physical Properties of Metalloids: have properties of both metals and nonmetals. Solid, shiny or dull, ductile and malleable, conduct heat and electricity, but not very well.

25. INCREASING REACTIVITY The Periodic Table • Where are the following? • Metals • Non-metals • Transition metals • Metalloids See page 172 (c) McGraw Hill Ryerson 2007

26. Organization of the Periodic Table • Rows of elements (across) are called periods. • All elements in a period have their electrons in the same general area around their nucleus. • Example: period 3 all have 3 electron shells sodium magnesium aluminum See page 171 (c) McGraw Hill Ryerson 2007

27. Organization of the Periodic Table • Columns of elements are called groups, or families. • All elements in a family have similar properties and bond with other elements in similar ways. • Group 1 = alkali metals • Group 2 = alkaline earth metals • Group 17 = the halogens • Group 18 = noble gases 18 1 2 17 See page 171 (c) McGraw Hill Ryerson 2007

28. Organization of the Periodic Table Group 1 = alkali metals very reactive metals want to give away 1 electron ie: lithium, sodium, potassium... 18 1 2 17 See page 171 (c) McGraw Hill Ryerson 2007

29. Organization of the Periodic Table Group 2 = alkali earth metals somewhat reactive metals want to give away 2 electrons ie: beryllium, magnesium, calcium... 18 1 2 17 See page 171 (c) McGraw Hill Ryerson 2007

30. Organization of the Periodic Table Group 17 = halogens very reactive non-metals want to accept 1 electron react with alkali metals ie: fluorine, chlorine, bromine...... 18 1 2 17 See page 171 (c) McGraw Hill Ryerson 2007

31. Organization of the Periodic Table Group 18 = noble gases STABLE. Very non reactive gaseous non-metals ie: helium, neon, argon...... 18 1 2 17 See page 171 (c) McGraw Hill Ryerson 2007

32. INCREASING REACTIVITY The Periodic Table • Where are the following? • Period • Group/Family • Alkali metals • Alkaline earth metals • Halogens • Noble gases See page 172 (c) McGraw Hill Ryerson 2007

34. Periodic Table & Ion Formation • Atoms gain and lose electrons to form bonds. • The atoms become electrically charged particles called ions. See page 173 (c) McGraw Hill Ryerson 2007

35. Periodic Table & Ion Formation • Atoms gain and lose electrons to form bonds. • Metals lose negative electrons & become positive ions. • Positive ions are called CATIONS. See page 173 (c) McGraw Hill Ryerson 2007

37. Periodic Table & Ion Formation Some metals are MULTIVALENT and can lose a varying number of electrons. For example, iron, Fe, loses either two (Fe2+) or three (Fe3+) electrons See page 173 (c) McGraw Hill Ryerson 2007

38. Periodic Table & Ion Formation • Atoms gain and lose electrons to form bonds. • Non-metals gain electrons and become negative ions • Negative ions are called ANIONS See page 173 (c) McGraw Hill Ryerson 2007

39. Periodic Table & Ion Formation Atoms gain and lose electrons in an attempt to be STABLE. The noble gases are stable because they have FULL outer shells of electrons. They don’t need to lose or gain any e-s. Atoms in each period want to have the same number of electrons in their outer shell (VALENCE ELECTRONS) as the noble gases on the end of their period. See page 173 (c) McGraw Hill Ryerson 2007

40. BOHR MODELS • Bohr diagrams show how many electrons appear in each electron shell around an atom. • The first electron shell holds 2 electrons • The second electron shell holds 8 electrons • The third electron shell holds 8 electrons • The fourth electron shell holds 18 electrons • The noble gas elements have full electron shells and are very stable. See page 174 (c) McGraw Hill Ryerson 2007

41. Patterns of Electron Arrangement in Periods & Groups • Electrons appear in shells in a very predictable manner. • The period number = the number of shells in the atom. • Except for the transition elements (family 3-12), the last digit of the group number = the number of electrons in the valence shell. See page 175 (c) McGraw Hill Ryerson 2007

42. BOHR MODELS 18 p 22 n What element is this? argon • It has 2 + 8 + 8 = 18 electrons, and therefore, 18 protons. • It has three electron shells, so it is in period 3. • It has eight electrons in the outer (valence) shell. See page 174 (c) McGraw Hill Ryerson 2007

44. Forming Compounds • When two atoms get close together, their valence electrons interact. • If the valence electrons can combine to form a low-energy bond, a compound is formed. • Each atom in the compound attempts to have a ‘full’ outer shell of valence electrons. See pages 176 - 177 (c) McGraw Hill Ryerson 2007

45. Forming Compounds There are 2 types of compounds: • IONIC COMPOUND: metals lose electrons and non-metals gain electrons. • Ionic bonds form when electrons are transferred from positive (+) ions to negative (-) ions. • The negative and positive ions are ATTRACTED to each other and form a BOND. See pages 176 - 177 (c) McGraw Hill Ryerson 2007

48. Forming Compounds • Example ionic bond: • lithium and oxygen form an ionic bond in the compound Li2O. + Electrons are transferred from the positive ions to negative ions Li+ O2- Li+ lithium oxide, Li2O oxygen lithium See pages 176 - 177 (c) McGraw Hill Ryerson 2007

49. Forming Compounds There are 2 types of compounds: • COVALENT COMPOUND: atoms share electrons. • Covalent bonds form when electrons are shared between two non-metals. • Electrons stay with their atom but overlap with other shells. See pages 176 - 177 (c) McGraw Hill Ryerson 2007