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Chemistry: THE STUDY OF MATTER

Chemistry: THE STUDY OF MATTER. So what is matter?. Matter. Must have mass It is different from weight…..Why? Must occupy space (have volume ). Matter Has Density. Density of a Substance = Mass Volume See Reference Table S to compare density of elements. States of Matter.

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Chemistry: THE STUDY OF MATTER

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  1. Chemistry:THE STUDY OF MATTER

  2. So what is matter?

  3. Matter • Must have mass • It is different from weight…..Why? • Must occupy space (have volume)

  4. Matter Has Density • Density of a Substance = Mass Volume See Reference Table S to compare density of elements

  5. States of Matter • Matter can exist in three basic states: • Solid (s), Liquid (l), Gas (g) • How are these states different from each other?

  6. Can Matter be Destroyed? Example: • When 400 grams of wood are burned only about 30 grams of ash remain. • What would you think? • What happened to the missing matter?

  7. Law of Conservation of Matter • Matter cannot be created or destroyed Matter isn’t being lost but changing in form!

  8. Atoms are all still there they just get rearranged

  9. Balanced chemical equations show the number of atoms stay the same during reactions and thus obey this law.

  10. Basic Types of Matter: Elements vs. Compounds

  11. Elements • Made of atoms of one specific type • Cannot be broken down chemically • Have specific properties.

  12. Examples of Elements

  13. Where Do We Get Elements? • Obtained in nature in their pure state.

  14. Found combined with other elements in compounds

  15. Man-made through nuclear bombardment reactions

  16. Elements and Their Symbols • Take Note Please! • Elements have either one or two letters when they are written as a symbol. • If two letters, the second letter is written lower case. (Ex: Write Cu for copper not CU) • Why is this so important?

  17. Usually it is pretty easy to match an element to its symbol (Ex: Neon = Ne) • Sometimes the symbol is derived from a Latin name for the element. • Ex: Au = gold (comes from Latin word aurum)

  18. Na = sodium K = potassium Fe = iron Cu = copper Sb = antimony Sn = tin Pb = lead Hg = mercury W = tungstun Au = gold Ag = silver Tricky Elements

  19. Phases and Elements • Solids: • Most elements are solids • Gases: • H, He, Ne, Ar, Kr, Xe, Rn, N, O, F, Cl • Liquids: • Hg, Br • Let’s make a note of these on our Periodic Tables!

  20. Diatomic Elements • Most elements are monoatomic in pure form. • Some elements have two atoms joined (diatomic) Who are they? • Remember BrINClHOF • Let’s make a note of these on our Periodic Tables!

  21. Compounds • Two or more different elements bonded together chemically Ex: C6H12O6, NO2, CO2, NaCl • Note: Most elements in nature do not exist in their pure state, but in compounds. • Why?

  22. Law of Definite Proportions • Compounds have specific formulas that show the proportion of elements to each other. • Ex: Water is always H2O • A “mixture” has proportions that can vary • Ex: salt water

  23. Getting New Properties • Compounds have different chemical and physical properties than the elements that make them up.

  24. - Sodium (Na) Toxic metal - Chlorine (Cl) Toxic gas Sodium Chloride (NaCl) White edible crystal salt for my french fries!!

  25. Focus Question • What makes atoms of one element different from another? • What is inside its atoms…

  26. Atomic Basics • Atoms consist of three basic parts. • Protons • Neutrons • Electrons

  27. Fill in Chart:

  28. Atomic Number: • Tells us the number of protons in nucleus • It is unique for each element

  29. Does an Atom Have a Charge? • Atoms are neutral particles • Number of electrons (-) = number of protons (+) • How many electrons does an atom of carbon have?

  30. Nuclear Charge: the charge on the nucleus of the atom. (+) positive charge = to number of protons Does the Nucleus have a Charge? What is the Nuclear Charge? What is the Atomic Number? What is this Element?

  31. Atoms vs. Ions • Ions: atoms with a charge • Protons don’t equal electrons!! • Atom has gained or lost electrons • Gain electrons: become (-) ion • Lose electrons: become (+) ion P = 9 E = 10 What is the element? What is it’s ionic charge?

  32. Ionic Charge Practice Try a few for practice…

  33. Atomic Mass Number • Atomic Mass Number: • Sum of the number of protons + neutrons • Each has a mass of 1 amu. (atomic mass unit) Ex: P = 23 N = 21 What is the Atomic Mass Number? What is this element?

  34. Isotopes • Isotopes: atoms of the same element with different atomic mass. • Same # protons • Different # neutrons • Ex: Carbon-12, Carbon-14 (two isotopes of C) • How many protons? • How many neutrons?

  35. Average Atomic Mass • Average Atomic Mass: • The atomic mass you see on the periodic table • Based upon abundance of isotope and its mass in an sample of the element

  36. Calculating Average Atomic Mass • Mass of each isotope x abundance (change % abundance to decimal) • Add together answers • Ex: Chlorine

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