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Ch 2 Matter & Atoms

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  1. Ch 2 Matter & Atoms Natural Approach to Chemistry Lab Aids Condensed 2.1 Frames 2-28 2.2 Frames 29-62 2.3 Fr. 63-106

  2. 2.1 Matter & the Elements • Standards: • SC.912.P.8.5 relate properties of atoms & their position in the periodic table to the arrangement of their electrons • SC.912.P.8.9 apply the mole concept and the law of conservation of mass to calculate quantities of chemicals participating in reactions

  3. What are things made of? The “stuff” that we are made of is calledmatter. Chemistry tells us how one kind of matter can be changed into a completely different kind of matter.

  4. Corn oil is a pure substance substance: a kind of matter that can’t be separated into other substances by physical means such as heating, cooling, filtering, drying, sorting, or dissolving.

  5. Oil and vinegar dressing is a mixture of substances Corn oil is a pure substance mixture: matter that contains more than one substance.

  6. Physical properties Examples: Mass Density Color Physical propertiescan be measured or seen through direct observations.

  7. Physical changes include changes in shape, phase or temperature.

  8. Chemical propertiesare observed when a substance changes into a different substance. Chemical change Iron Rust

  9. Signs that a chemical change has occurred

  10. element: a substance that cannot be separated into simpler substances by chemical means. Each element is a unique type of atom. All oxygen atoms are identical. An oxygen atom is different from a silicon atom or a potassium atom.

  11. How small is an atom? 1 grain of rice = 0.01 gram 1 hydrogen atom = 1.678 x 10–24 grams = 0.000000000000000000000001678 grams

  12. The periodic table

  13. The periodic table organizes elements according to how they combine with other elements (based on their chemical properties).

  14. Increasing atomic number Increasing atomic number Hydrogen Lightest element Atomic number: 1 Uranium Heaviest naturally occurring element Atomic number: 92

  15. Elements that belong to the same group (column) have similar chemical properties.

  16. Reminder 1 atomic mass unit (amu) = 1.66 x 10-24 g

  17. The atomic mass is • the mass of: • a single atom in amu. • a mole of atoms in grams. What does that mean? One singlehydrogen atom weighs 1.01 amu. One mole of hydrogen atoms weighs 1.01 g.

  18. The atomic mass is • the mass of: • a single atom in amu. • a mole of atoms in grams. What does that mean? One singlecarbon atom weighs 12.0 amu. One mole of carbon atoms weighs 12.0 g.

  19. Avogadro’s number One mole contains 6.02 x 1023 atoms

  20. How many moles are in 100 g of sulfur (S)?

  21. How many moles are in 100 g of sulfur (S)? Asked: The number of moles Given: The element is sulfur and there are 100 g Relationships: One mole of sulfur has a mass of 32.065 g

  22. How many moles are in 100 g of sulfur (S)? Asked: The number of moles Given: The element is sulfur and there are 100 g Relationships: One mole of sulfur has a mass of 32.065 g Solve: Answer: 100 g of sulfur contains 3.12 moles of sulfur atoms.

  23. How many grams of calcium (Ca) do you need to have 2.50 moles of calcium? Asked:The number of grams Given:The element is calcium and there are 2.50 moles Relationships:One mole of calcium has a mass of 40.078 g

  24. How many grams of calcium (Ca) do you need to have 2.50 moles of calcium? Asked: The number of grams Given: The element is calcium and there are 2.50 moles Relationships: One mole of calcium has a mass of 40.078 g Solve: Answer: 2.50 moles of calcium has a mass of 100. g.

  25. Physical properties can be seen and measured Chemical properties are observed when one substance is changed into another Elements are organized in a periodic table This allows to convert grams to moles and vice versa.

  26. 2.2 Molecules and Compounds Sc.912.P.8.7 interpret formula representations of molecules and compounds in terms of composition and structure. Sc.912.P.8.9 mole concept and law of conservation of mass

  27. One O2 molecule One H2 molecule molecule: a group of atoms chemically bonded together.

  28. One O2 molecule One H2 molecule One H2O molecule molecule: a group of atoms chemically bonded together. compound: a substance containing more than one element in which atoms of different elements are chemically bonded together.

  29. What do all these have in common?

  30. What do all these have in common? They are made up of only 3 types of atoms: carbon, oxygen and hydrogen.

  31. The alphabet of chemistry More than 200,000 words in the English language Trillions of substances that make up the universe

  32. The chemical formula

  33. The chemical formula

  34. Write a chemical formula for a compound that has three hydrogen (H) atoms for each atom of nitrogen (N).

  35. Write a chemical formula for a compound that has three hydrogen (H) atoms for each atom of nitrogen (N). Asked: Chemical formula Given: 3 hydrogen (H) and 1 nitrogen (N) Relationships: The subscript tells the number of each element in the compound.

  36. Write a chemical formula for a compound that has three hydrogen (H) atoms for each atom of nitrogen (N). Asked: Chemical formula Given: 3 hydrogen (H) and 1 nitrogen (N) Relationships: The subscript tells the number of each element in the compound. Answer:NH3

  37. The properties of a compound depend more on the exact structure of the molecule than on the individual elements from which it is made.

  38. F R A N E U L F U N E R A L R E A L F U N The arrangement of letters matters!

  39. The arrangement of atoms matters!

  40. Representation There are many ways of representing the same thing.

  41. Representation

  42. Ionic compounds Salt (NaCl) is not a molecule!

  43. ionic compound: a compound such as a salt in which positive and negative ions attract each other to keep matter together. ion: an atom or small molecule with an overall positive or negative chare as a result of an imbalance of protons and electrons.

  44. Formula mass The formula mass of water (H2O) is 18 g.

  45. What is the mass of 1 mole of methane (CH4)?

  46. What is the mass of 1 mole of methane (CH4)? Asked: The mass of 1 mole of methane Given:Methane (CH4) contains 1 carbon (C) and 4 hydrogen (H) atoms Relationships: The formula mass is the sum of the atomic masses for each atom in the compound

  47. What is the mass of 1 mole of methane (CH4)? Asked: The mass of 1 mole of methane Given: Methane (CH4) contains 1 carbon (C) and 4 hydrogen (H) atoms Relationships: The formula mass is the sum of the atomic masses for each atom in the compound Solve: Answer: One mole of methane (CH4) has a mass of 16.04 g.