1. Atomic Structure

2. Matter Anything that has mass and takes up space Matter can take many forms and is not always visible to the eye Matter can change form

3. Matter is made of atoms Matter can neither be created nor destroyed; it just changes form - Law of Conservation of Matter

4. Atoms Tiny particles that make up matter They are so small that 1 million atoms lined up side by side are equal to the thickness of a human hair

5. “atom” comes from a Greek word that means “cannot be divided” Atoms are made of small subatomic particles called protons, electrons, and neutrons

6. Proton Positively charged particle Located in the nucleus of an atom Mass = 1 atomic mass unit Number: the number of protons equals the number of electrons

7. Electron Negatively charged particle Located outside the nucleus of an atom Mass is almost 0 (1/2000 of a proton) Number: the number of electrons equals the number of protons

8. Neutron Neutral particle, no charge Located in the nucleus of an atom Mass = 1 atomic mass unit Number: the number of neutrons varies

9. Nucleus Contains most of the mass of an atom Total number of particles in the nucleus is equal to the number of protons plus the number of neutrons

10. Model of the Atom Protons and neutrons are found in the nucleus, the dense center of an atom Nucleus is positively charged - protons are positively charged and neutrons have no charge

11. Electrons are found in a cloud around the positively charged nucleus The electrons are very far away from the nucleus, so the atom is mostly empty space

13. Nucleus Most of the mass of the atom is located in the nucleus because electrons are so small compared to mass of protons and neutrons

14. Electrons Electrons are arranged in energy levels around the nucleus, these are sometimes called energy shells Electrons are negatively charged particles

15. Lowest energy level is closest to the nucleus and can contain only 2 electrons Higher energy levels, further from the nucleus can contain more electrons

16. Level 2 can hold 8 electrons, level 3 can hold up to 18, and level 4 up to 32 There are up to 7 energy levels for electrons

17. Types of Matter - Elements Most kinds of matter are made of combinations of a basic group of building blocks called elements Element - matter made up of only one type of atom

18. Natural elements There are about 112 known elements today; 90 of these are naturally occurring elements, the rest are synthetic Naturally occurring elements are found in nature

19. Synthetic elements Synthetic elements are man- made in laboratories. These elements may exist naturally in stars, but on Earth they exist only when made in a lab Synthetic elements are unstable

20. Periodic table Elements are organized into a chart called the periodic table They are organized by the number of protons in their nuclei Mendeleev came up with the idea of classifying elements into a table

21. Element name and symbol Each element has a name and an abbreviation known as its atomic symbol Atomic symbols consist of 1, 2, or 3 letters. The first letter of the symbols is capitalized and the rest are lower case

22. New synthetic elements have the 3 letter symbol that represents their number and later are assigned a 2 letter symbol For example Element 114 was called Ununquadium, Uuq, until it got its final name Flerovium, Fl

23. Atomic number The atomic number of an element indicates the number of protons in the nucleus of that element

24. Atoms are electrically neutral The number of protons is equal to the number of electrons

25. Atomic mass of an atom The atomic mass is a number that indicates the mass of the atoms of that element in atomic mass units, symbolized by the letter u Atomic mass is equal to the number of protons + the number of neutron in the nucleus

26. Information on the periodic table Element name -----> Atomic number ----> Atomic symbol ----> Atomic mass ------> Chlorine 17 Cl 35.453

27. Isotopes All the atoms of an element have the same number of protons There are different forms of an element called isotopes Isotopes differ from each other because they have different numbers of neutrons

28. Isotopes Isotopes have the same number of protons, but different numbers of neutrons Isotopes have different masses

29. Isotopes C-12 and C-14 are isotopes of carbon C-12 or Carbon-12, has a mass of 12 u, 6 protons and 6 neutrons C-14 or Carbon-14, has a mass of 14 u, 6 protons and 8 neutrons

30. Isotopes Isotopes are named by writing the name or symbol for the element followed by a hyphen and the atomic mass of the element Ag-107 is silver with an atomic mass of 107, protons 47, neutrons 60

31. Average atomic mass Because elements have various isotopes, the atomic mass reported in the Periodic Table is an average of the masses of the various isotopes of the element

32. Average atomic mass The amounts (percentages) of each isotope in a sample is accounted for when the average atomic mass is calculated

33. Ions Atoms that have the same number of electrons and protons are neutral and have no charge Sometimes atoms can be positively or negatively charged – atoms that have a charge are called ions

34. Ions Ions with more electrons than protons are negatively charged Ions with more protons than electrons are positively charged

35. Ions: anions Negative ions are called anions O 2-, Oxygen ion with 8 protons and 10 electrons, has a charge of -2

36. Ions: cations Positive ions are called cations Mg 2+ Magnesium ion with 12 protons and 10 electrons, it has a charge of +2

37. Atomic identity Number of protons controls the identity of an element Change the number of protons and you change to a new element

38. Atomic reactivity Number of electrons controls the reactivity of an element Atoms can add or lose electrons and still keep their identity Atoms that add or lose electrons are charged and are called ions

39. Periodic Table Mendeleev, a Russian scientist first organized all the elements known in the late 1800’s He discovered repeating patterns in chemical properties He arranged the elements in order of increasing atomic mass

40. Modern Periodic Table The periodic table is a table of the chemical elements in which the elements are arranged in order of atomic number in such a way that the periodic properties (chemical periodicity) of the elements are made clear.

41. Modern Periodic Table Elements are arranged in order of increasing atomic number Increase in atomic number from left to right

42. Modern Periodic Table - Periods Rows are called periods (horizontal) Elements in the same period have the same number of energy levels for their electrons

43. Modern Periodic Table - Groups Columns are called groups or families (vertical) Elements in the same column have similar chemical properties They have different numbers of electrons, but the same number of outer (valence) electrons

44. Modern Periodic Table Metals are to the left of the periodic table Non-metals to the right Metalloids are stair steps on right, between metals and non-metals

46. Periods Numbered from 1 to 7 6 th and 7 th periods also contain the rows at the bottom of the table

47. Groups Numbered from 1 to 18 Also called families Each group of elements has characteristic chemical and physical properties that can assist in their identification

48. Group 1 Alkali metals Easily react with water 1 valence electron Hydrogen is in Group 1 because it has 1 valence electron, but it is not a metal

49. Group 17 Halogens Extremely reactive 7 valence electrons Nonmetals Tend to form negative ions and gain 1 electron

50. Group 18 Noble or Inert Gases Extremely unreactive, usually don’t bond with other elements 8 valence electrons (He has 2) Outer energy level can’t hold any more electrons Nonmetals

51. Metals Groups 1-12 and parts of 13-17 Shiny or lustrous in appearance, hard, malleable, ductile (can be pulled into wires) Conduct heat and electricity very well

52. Metals Tend to form positive ions and give away or share 1 to 4 electrons Most of the elements in the Periodic Table are metals Find them on the left and the center of the Table

53. Nonmetals Can be gases or solids at room temperature Belong to Groups 14 - 18 Find them on the upper right corner of the Periodic Table

54. Nonmetals Soft, brittle, and dull in appearance Poor conductors of heat or electricity Can share electrons or gain 1, 2, or 3 electrons to form negative ions

55. Metalloids Select elements in Groups 13-17 B, Si, Ge, As, Sb, Te, Po, and At Found along the boundary between metals and nonmetals, along a stairstep Not all scientists agree as to the exact elements in this group

56. Metalloids Can be shiny or dull, soft or hard, malleable or brittle Can conduct electricity, but not as well as metals (semi-conductors)

57. Chemical Reactivity An example of chemical reactivity is when two or more elements combine to form compounds or molecules (if two of the same elements bond together)

58. Inorganic Compounds Compounds of metal atom(s) and one or more nonmetal atoms Often form ionic bonds with metal cation(s) (+) and nonmetal anion(s) (-) Result in a neutral compound, also called a salt

59. Organic Compounds Compounds that do not usually contain metal atoms Often have C and H atoms bonded together by covalent (shared electrons) bonds Also contain O, N, and S