1. Elements and the Periodic Table Introduction to Atoms

2. IB Unit Question How can we use patterns trends and relationships to organize our world?

3. Atomic Models Democritus; Greek philosopher who lived around the year 430 B.C. He proposed the idea that matter is formed of small pieces that could not be cut into smaller parts. Atomos: Greek word meaning ‘uncuttable’. This is where we get the word Atom.

4. Dalton’s Atomic Theory John Dalton, English chemist, proposed an atomic theory and model for atoms. Dalton thought that atoms where smooth, hard balls that could not be broken into smaller pieces.

5. Dalton’s Atomic Theory All elements are composed of atoms that cannot be divided (broken down into smaller pieces) All atoms of the same element are exactly alike and have the same mass. Atoms of different elements are different and have different masses. An atom of one element cannot be changed into an atom of a different element. Atoms cannot be created or destroyed in any chemical change, only rearranged.

6. Dalton’s Atomic Theory Every compound is composed of atoms of different elements, combined in a specific ratio.

7. Thomson and the smaller parts of atoms J.J. Thomson, British scientist, 1897. Discovered that atoms contain negatively charged particles. Since scientists knew that atoms had no electrical charge he inferred that atoms must also have some sort of positive charge.

8. Thomson and smaller parts of atoms continued.... He proposed a model that described an atom something like a blueberry muffin. The berries (negative) are scattered throughout a ball of positive charge. The negatively charged particles later became known as electrons.

9. Rutherford and the Nucleus Ernest Rutherford, student of Thomson, 1911. He used a thin sheet of gold foil and a particle beam of positive particles to show that an atom’s positive charge must be clustered in a tiny region in its center. We now call that region of positive charge at the center of an atom the nucleus.

10. Rutherford continued... Scientists knew that electrons had almost no mass. They reasoned that nearly all of an atom’s mass must also be located in the tiny, positively charged nucleus. Rutherford named these positively charged particles, found in the nucleus, protons.

11. Bohr’s Model Niels Bohr, Danish scientist, 1913; student of both Thomson and Rutherford. Bohr showed that electrons could have only specific amounts of energy, leading them to move in certain orbits. These orbits resemble planets orbiting a sun.

12. Cloud of Electrons In the 1920’s scientists determined that electrons do not orbit the nucleus like planets. Instead, they can be found anywhere in a cloudlike region around the nucleus. (the cloud is a visual model) An electron’s movement is related to its energy level. or specific amount of energy it has. Electrons of different energy levels are likely to be found in different places of the ‘cloud’.

14. The Modern Atomic Model James Chadwick, 1932, British scientist; discovered a new particle in the nucleus of atoms. This new particle has about the same mass as a proton. This new particle has no electrical charge This particle was called a neutron.

15. Modern Atomic Model continued... The modern model describes an atom as consisting of a nucleus that contains protons and neutrons, surrounded by a cloud-like region of moving electrons

16. Modern Atomic Model continued... Particle Charges The number of protons always equals the number of electrons. This ensures that the overall atom is neutral. The number of neutrons does not have to equal the number of protons. Neutrons don’t affect the charge of an atom because they have no charge.

17. Modern Atomic Model continued... Comparing particle masses It takes almost 2000 electrons to equal the mass of just one proton. A proton and a neutron are about equal in mass. Atoms are too small to describe with everyday units of mass (grams, kilograms). Scientists use units known as Atomic Mass Units (AMU) to describe the mass of atoms and its particles.

18. Modern Atomic Model continued... Comparing particle masses A proton or neutron has a mass equal to about one amu (atomic mass unit).

19. Modern Atomic Model continued... Scale and Size of Atoms Most of the volume of an atom is the space in which the electrons move (electron cloud). The nucleus is extremely small compared to the size of the overall atom. In a speck of dust there may be 10 million billion atoms.

20. Modern Atomic Model continued... Atomic Number Every atom of an element has the same number of protons. Ex/ Every atom of carbon (C) has 6 protons. The number of protons in the nucleus is called the Atomic Number. Atomic number identifies an element.

21. Modern Atomic Model continued... Isotopes and Mass Number All atoms of an element have the same number of protons. However, they may have different number of neutrons. Atoms with the same number of protons and a different number of neutrons are called isotopes. An isotope is identified by its mass number, which is the sum of the protons and neutrons in the nucleus.

22. Organizing the Elements Patterns in the Elements Dmitri Mendeleev, Russian scientist Discovered a set of patterns that applied to all the elements

23. Mendeleev’s Work Noticed that a pattern of properties appeared when he arranged the elements in order of increasing atomic mass Noticed that a pattern of properties appeared when he arranged the elements in order of increasing atomic mass Atomic Mass: is the average mass of all the isotopes of an element. Atomic Mass: is the average mass of all the isotopes of an element.

24. Organization of the Periodic Table Properties of an element can be predicted from its location on the periodic table. Properties of an element can be predicted from its location on the periodic table. Periods: are the horizontal rows of the PT Periods: are the horizontal rows of the PT Groups: are the vertical columns of the PT Groups: are the vertical columns of the PT

25. Reading an elements square Each square on the periodic table consists of the following: Each square on the periodic table consists of the following: Atomic Number: number of protons Atomic Number: number of protons Chemical Symbol: abbreviation of chemical name; sometimes abbreviated English name and sometimes its Latin name Chemical Symbol: abbreviation of chemical name; sometimes abbreviated English name and sometimes its Latin name Atmomic Mass: average atomic mass of all the elements isotopes Atmomic Mass: average atomic mass of all the elements isotopes

26. How Elements Form in Stars Plasma: state of matter that consists of a gas-like mixture of free electrons and nuclei of atoms that have been stripped of electrons. Plasma: state of matter that consists of a gas-like mixture of free electrons and nuclei of atoms that have been stripped of electrons. Nuclear Fusion: occurs in stars where smaller nuclei are ‘fused’ together in larger nuclei. Nuclear Fusion: occurs in stars where smaller nuclei are ‘fused’ together in larger nuclei.

27. Metals: Properties of Metals Physical Properties: Physical Properties: Shininess Shininess Malleability Malleability Ductility Ductility Conductivity Conductivity

28. Metals: Properties of Metals Malleable: ability to be hammered or rolled into shapes. Malleable: ability to be hammered or rolled into shapes. Ductile: ability to be pulled out into wire. Ductile: ability to be pulled out into wire. Conductivity: ability to transfer heat or electricity to another object. Conductivity: ability to transfer heat or electricity to another object.

29. Metals: Properties of Metals Chemical Properties: Chemical Properties: Reactivity: the ease and speed which an element combines, or reacts, with other elements and compounds. Reactivity: the ease and speed which an element combines, or reacts, with other elements and compounds. Metals react by losing electrons to other atoms. Metals react by losing electrons to other atoms. Corrosion: the destruction of a metal by reacting with oxygen. Corrosion: the destruction of a metal by reacting with oxygen.

30. Metals in the Periodic Table The reactivity of metals tend to decrease as you move from left to right across the periodic table The reactivity of metals tend to decrease as you move from left to right across the periodic table

31. Metals in the Periodic Table Alkali Metals: Alkali Metals: Metals in group 1 Metals in group 1 React with other elements by losing one electron React with other elements by losing one electron These metals are so reactive that they are never found uncombined in nature, instead they are only found in compounds. These metals are so reactive that they are never found uncombined in nature, instead they are only found in compounds. Shiny and soft Shiny and soft

32. Metals in the Periodic Table Alkali Metals Continued: Alkali Metals Continued: Sodium (Na): found in large amounts in seawater and salt beds and is important part of your diet Sodium (Na): found in large amounts in seawater and salt beds and is important part of your diet Lithium (Li): used in batteries and some medicines Lithium (Li): used in batteries and some medicines

33. Metals in the Periodic Table Alkaline Earth Metals Alkaline Earth Metals Group 2 Group 2 Fairly hard, gray-white and good conductors of electricity Fairly hard, gray-white and good conductors of electricity Not as reactive as group 1, but more reactive than most other metals Not as reactive as group 1, but more reactive than most other metals Never found uncombined in nature Never found uncombined in nature

34. Metals in the Periodic Table Alkaline Earth Metals Continued: Alkaline Earth Metals Continued: Two of the most common are magnesium (Mg) and calcium (Ca) Two of the most common are magnesium (Mg) and calcium (Ca) Calcium important to healthy teeth and bones and helps muscles work properly. Found in milk and other dairy products and green, leafy vegetables. Calcium important to healthy teeth and bones and helps muscles work properly. Found in milk and other dairy products and green, leafy vegetables. Magnesium and aluminum make strong, light weight metal used in ladders and airplanes Magnesium and aluminum make strong, light weight metal used in ladders and airplanes

35. Metals in the Periodic Table Transition Metals Transition Metals Groups 3 through 12 Groups 3 through 12 Include metals such as iron, copper, nickel, silver, and gold Include metals such as iron, copper, nickel, silver, and gold Most are hard and shiny. Most are hard and shiny. All transition metals are good conductors of electricity All transition metals are good conductors of electricity Many form colorful compounds Many form colorful compounds

36. Metals in the Periodic Table Transition Metals Continued Transition Metals Continued Less reactive than metals in Groups 1 and 2 Less reactive than metals in Groups 1 and 2

37. Metals in the Periodic Table Metals in Mixed Groups Metals in Mixed Groups Only some of the metals in Groups 13 – 15 are metals Only some of the metals in Groups 13 – 15 are metals Not as reactive as metals on the left side of the Periodic Table Not as reactive as metals on the left side of the Periodic Table Most familiar are aluminum, tin and lead Most familiar are aluminum, tin and lead

38. Metals in the Periodic Table Lanthanides Lanthanides Soft, malleable, shiny metals with high conductivity Soft, malleable, shiny metals with high conductivity They are mixed with more common metals to make alloys. They are mixed with more common metals to make alloys. Alloys: are mixtures of a metal with at least one other element, usually another metal Alloys: are mixtures of a metal with at least one other element, usually another metal

39. Metals in the Periodic Table Actinides Actinides Of the actinides only actinium (Ac), thorium (Th),protactinium (Pa), and uranium (U) occur naturally Of the actinides only actinium (Ac), thorium (Th),protactinium (Pa), and uranium (U) occur naturally ALL elements after uranium are made in laboratories. Their nuclei are very unstable, meaning they break apart very quickly into smaller nuclei. ALL elements after uranium are made in laboratories. Their nuclei are very unstable, meaning they break apart very quickly into smaller nuclei.

40. Metals in the Periodic Table Synthetic Elements Synthetic Elements Elements with atomic numbers greater than 92 Elements with atomic numbers greater than 92 Made by forcing nuclear particles to crash into each other. Made by forcing nuclear particles to crash into each other. Examples: Plutonium= U-238 + Neutrons Examples: Plutonium= U-238 + Neutrons Americium-241 (Am-241) = Americium-241 (Am-241) = Plutonium nuclei + Neutrons Plutonium nuclei + Neutrons

41. Metals in the Periodic Table Synthetic Elements continued Synthetic Elements continued To make elements above atomic number 95 scientists use Particle Accelerator. To make elements above atomic number 95 scientists use Particle Accelerator.

42. Nonmetals and Metalloids Properties of Nonmetals A nonmetal lacks most of the properties of a metal. A nonmetal lacks most of the properties of a metal. Poor conductors of electricity and heat Poor conductors of electricity and heat Solid nonmetals are dull and brittle Solid nonmetals are dull and brittle

43. Nonmetals and Metalloids Properties of Nonmetals Physical Properties Physical Properties 10 of the 16 nonmetals are gases at room temperature. 10 of the 16 nonmetals are gases at room temperature. Bromine (Br) is the only nonmetal that is liquid at room temperature Bromine (Br) is the only nonmetal that is liquid at room temperature

44. Nonmetals and Metalloids Properties of Nonmetals Physical Properties continued Physical Properties continued Solid nonmetals are dull (not shiny), and brittle (not malleable or ductile) Solid nonmetals are dull (not shiny), and brittle (not malleable or ductile) Usually have lower densities than metals Usually have lower densities than metals Poor conductors of electricity and heat Poor conductors of electricity and heat

45. Nonmetals and Metalloids Properties of Nonmetals Chemical Properties Chemical Properties Most nonmetals are reactive (readily form compounds) Most nonmetals are reactive (readily form compounds) Fluorine (F) is the most reactive element known Fluorine (F) is the most reactive element known Atoms of nonmetals usually gain or share electrons when they react with other atoms. Atoms of nonmetals usually gain or share electrons when they react with other atoms. Many nonmetals can also for compounds with other nonmetals. They share electrons and become bonded together into molecules Many nonmetals can also for compounds with other nonmetals. They share electrons and become bonded together into molecules

46. Families of Nonmetals The Carbon Family The Carbon Family Each element in this family can gain, share or lose 4 electrons when reacting with other elements Each element in this family can gain, share or lose 4 electrons when reacting with other elements Only Carbon is a nonmetal Only Carbon is a nonmetal Carbon is important in the chemistry of life Carbon is important in the chemistry of life Most fuels that are burned contain carbon Most fuels that are burned contain carbon

47. Families of Nonmetals The Nitrogen Family The Nitrogen Family This family contains 2 nonmetals (nitrogen and phosphorus) This family contains 2 nonmetals (nitrogen and phosphorus) These elements gain or share 3 electrons when reacting with other elements These elements gain or share 3 electrons when reacting with other elements The atmosphere is almost 80% Nitrogen The atmosphere is almost 80% Nitrogen

48. Families of Nonmetals The Nitrogen Family continued The Nitrogen Family continued Nitrogen is an example of an element that can occur as a diatomic molecule Nitrogen is an example of an element that can occur as a diatomic molecule Diatomic Molecule: consists of 2 atoms Diatomic Molecule: consists of 2 atoms Phosphorus is more reactive than nitrogen; in nature it is always found in compounds Phosphorus is more reactive than nitrogen; in nature it is always found in compounds

49. Families of Nonmetals The Oxygen Family The Oxygen Family Contains 3 nonmetals (oxygen, sulfur and selenium) Contains 3 nonmetals (oxygen, sulfur and selenium) Usually gain, share 2 electrons Usually gain, share 2 electrons Oxygen can exist as a diatomic and triatomic molecule Oxygen can exist as a diatomic and triatomic molecule Oxygen can combine with almost every other element (highly reactive) Oxygen can combine with almost every other element (highly reactive)

50. Families of Nonmetals The Oxygen Family continued The Oxygen Family continued Sulfur is a common nonmetal; used in the manufacturing of rubber. Sulfur is a common nonmetal; used in the manufacturing of rubber. Most sulfur is used to make sulfuric acid Most sulfur is used to make sulfuric acid

51. Families of Nonmetals The Halogen Family The Halogen Family Group 17 Group 17 Elements in this family are known as halogens, which means ‘salt formers’ Elements in this family are known as halogens, which means ‘salt formers’ All but astatine are nonmetals All but astatine are nonmetals All of the halogens are very reactive and the uncombined elements are harmful to humans All of the halogens are very reactive and the uncombined elements are harmful to humans

52. Families of Nonmetals The Halogen Family continued The Halogen Family continued Halogens typically share or gain one electron Halogens typically share or gain one electron Uses: Uses: Fluorine: dental health Fluorine: dental health

53. Families of Nonmetals The Halogen Family continued The Halogen Family continued Calcium Chloride: ice melt Calcium Chloride: ice melt Bromine: camera film (silver bromide) Bromine: camera film (silver bromide) Chlorine: kills bacteria in water Chlorine: kills bacteria in water

54. Families of Nonmetals The Noble Gases The Noble Gases Group 18 Group 18 Do not ordinarily form compounds; do not gain, share or lose electrons Do not ordinarily form compounds; do not gain, share or lose electrons

55. Families of Nonmetals Hydrogen Hydrogen Contains the simplest and smallest atoms Contains the simplest and smallest atoms One proton and one electron; some have neutrons One proton and one electron; some have neutrons 90% of the atoms in the universe; only 1% of mass of earth’s crust 90% of the atoms in the universe; only 1% of mass of earth’s crust

56. Metaloids Have some characteristics of both metals and nonmetals. Have some characteristics of both metals and nonmetals. All solids at room temperature All solids at room temperature Brittle, hard and somewhat reactive Brittle, hard and somewhat reactive Most common element: Silicon (Si); combines with oxygen to form SiO 2 ; ordinary sand is mostly Silicon dioxide Most common element: Silicon (Si); combines with oxygen to form SiO 2 ; ordinary sand is mostly Silicon dioxide

57. Metaloids Boron (B) used in glass making and some cleaning materials Boron (B) used in glass making and some cleaning materials Conduction depends on temperature, exposure to light or presence of small amounts of impurities. Conduction depends on temperature, exposure to light or presence of small amounts of impurities. Good for semiconductors (silicon, germanium (Ge) and arsenic (As) Good for semiconductors (silicon, germanium (Ge) and arsenic (As) Semiconductors: substances that can conduct electricity under some conditions but not under other conditions Semiconductors: substances that can conduct electricity under some conditions but not under other conditions