1 / 75

Chemistry Formulas: Valency, Atomic Mass, Moles

Learn about valency, atomic mass, and moles in chemistry, including formula calculations and word equations. Understand the relationships between elements and compounds. Practice drawing valency pictures and solving mole problems.

rudya
Download Presentation

Chemistry Formulas: Valency, Atomic Mass, Moles

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. S2 Chemistry Formula

  2. Valency • The valency of an atom is the number of links which it can form.

  3. Valency • Atoms usually have a valency of 1, 2, 3 or 4 • Magnesium has a valency of 2 and can be drawn as - Mg

  4. Valency

  5. Valency

  6. Valency

  7. Valency • Draw the valency pictures for – hydrogen silicon aluminium nitrogen oxygen carbon argon sulphur

  8. Valency • The formula of a compound can be obtained by using the valency pictures

  9. Valency • The formula of a compound can be obtained by using the valency pictures • Eg hydrogen oxide

  10. Valency • The formula of a compound can be obtained by using the valency pictures • Eg hydrogen oxide First draw the valency pictures for hydrogen and oxygen.

  11. Valency H hydrogen O oxygen

  12. Valency H hydrogen O oxygen

  13. Valency H hydrogen O H oxygen

  14. Valency H hydrogen O H2O H oxygen

  15. Valency H hydrogen O H2O H oxygen All the links must be used.

  16. Valency Eg magnesium oxide Mg O

  17. Valency Eg magnesium oxide Mg O MgO

  18. Relative Atomic Mass • Atoms of different elements are different in size and are different in mass.

  19. Naming Compounds • The first part of the name comes from the element that is furthest to the left of the periodic table

  20. Naming Compounds • The first part of the name comes from the element that is furthest to the left of the periodic table • If the compound contains only 2 elements, the second part of the name changes to end in -ide

  21. Relative Atomic Mass • Atoms of different elements are different in size and are different in mass. • The mass is too small to be measured in grams so it is given a relative value

  22. Relative Atomic Mass

  23. Relative Atomic Mass

  24. Relative Formula Mass • Compounds can be given a formula mass by adding up all the individual elements.

  25. Relative Formula Mass • Compounds can be given a formula mass by adding up all the individual elements. H2O 2 hydrogens = 2 x 1 = 2 1 oxygen = 1 x 16 = 16

  26. Relative Formula Mass • Compounds can be given a formula mass by adding up all the individual elements. H2O 2 hydrogens = 2 x 1 = 2 1 oxygen = 1 x 16 = 16 18

  27. The Mole • A mole of any element is the relative atomic mass in grams. • Eg a mole of carbon has a mass of 12g

  28. The Mole • A mole of any compound is the relative formula mass in grams. • Eg a mole of water has a mass of 18g

  29. The Mole • A mole of a substance is known as the gram formula mass (gfm)

  30. The Mole • The following triangle can be used for mole calculations Mass of substance mass Number of moles n gfm Mass of 1 mole

  31. The Mole - example • Calculate the mass of 3 moles of water

  32. The Mole • Calculate the mass of 3 moles of water • From the triangle mass = n x gfm

  33. The Mole H2O 2 hydrogens = 2 x 1 = 2 1 oxygen = 1 x 16 = 16 18

  34. The Mole • Calculate the mass of 3 moles of water • From the triangle mass = n x gfm mass = 3 x 18g

  35. The Mole • Calculate the mass of 3 moles of water • From the triangle mass = n x gfm mass = 3 x 18g mass = 54g

  36. The Mole • How many moles are present in 9g of water.

  37. The Mole • How many moles are present in 9g of water. • From the triangle n = mass/gfm

  38. The Mole • How many moles are present in 9g of water. • From the triangle n = mass/gfm n = 9/18

  39. The Mole • How many moles are present in 9g of water. • From the triangle n = mass/gfm n = 9/18 n = 0.5 moles

  40. Word Equations Learning Intention We are learning to write word equations

  41. Word Equations All chemical reactions can be described using a word equation eg reactants products (what you start with) (what you end up with)

  42. Word Equations eghydrogen + oxygen hydrogen oxide

  43. Word Equations • Write a word equation for the following reaction

  44. Word Equations • Write a word equation for the following reaction • Carbon dioxide is formed when carbon burns in oxygen.

  45. Word Equations • Write a word equation for the following reaction • Carbon dioxide is formed when carbon burns in oxygen. carbon + oxygen carbon dioxide

  46. Formula Equations • Instead of using words, the formula for the reactants and products can be used instead. This is called a formula equation. • carbon + oxygen carbon dioxide

  47. Formula Equations • Instead of using words, the formula for the reactants and products can be used instead. This is called a formula equation. • carbon + oxygen carbon dioxide C + O2 CO2

  48. Formula Equations • Eg hydrogen + oxygen hydrogen oxide

  49. Formula Equations • Eg hydrogen + oxygen hydrogen oxide H2 + O2 H2O

  50. Diatomic Elements • Certain elements always go around in pairs. These are the diatomic elements.

More Related