PERIODIC TABLE Chapter 5 1

ORGANIZING THE ELEMENTS Section 1 2

LET’S REVIEW! Chemical properties Chemical properties Any property that can only be tested by changing the chemical make-up of the substance. Any property that can only be tested by changing the chemical make-up of the substance. Physical properties Physical properties Any property that can be tested without changing the chemical make-up of the substance Any property that can be tested without changing the chemical make-up of the substance Atomic mass Atomic mass Mass of protons and neutrons Mass of protons and neutrons Atomic number Atomic number Unique to each element, same as number of protons Unique to each element, same as number of protons 3

DMITRI MENDELEEV 1870, there were 63 elements known to man 1870, there were 63 elements known to man He organized them in order of their atomic mass, and saw a pattern from their properties. He organized them in order of their atomic mass, and saw a pattern from their properties. Was working on this while Thomson and Rutherford were still “exploring” the atom Was working on this while Thomson and Rutherford were still “exploring” the atom 4

DMITRI MENDELEEV Arranged his table with repeating properties in columns, starting a new row each time the chemical properties repeated Arranged his table with repeating properties in columns, starting a new row each time the chemical properties repeated Left blank spaces in his table, concluding that these spaces were elements that hadn’t been discovered yet. Left blank spaces in his table, concluding that these spaces were elements that hadn’t been discovered yet. Based on the patterns and the other elements around the blank space, he predicted the properties of those elements Based on the patterns and the other elements around the blank space, he predicted the properties of those elements 5

AN EXAMPLE What he called ekasilicon – it was discovered a few years later 6 Prediction Atomic Mass72 amu Density5.5 g/mL Appearancedark gray metal Melting Pointhigh melting point Germanium 72.6 amu 5.3 g/mL gray metal 937 o C

MENDELEEV’S TABLE MENDELEEV’S TABLE 7

DMITRI MENDELEEV Some problems arose… Some problems arose… A few elements appeared to be slightly out of place A few elements appeared to be slightly out of place Mendeleev put them in the right place and said their atomic masses were incorrectly measured Mendeleev put them in the right place and said their atomic masses were incorrectly measured However, he was actually arranging them by the wrong number However, he was actually arranging them by the wrong number 8

HENRY MOSELEY 1910: Discovered atomic number 1910: Discovered atomic number He rearranged the periodic table by this number and it fell into perfect order He rearranged the periodic table by this number and it fell into perfect order Mendeleev’s table worked because as the number of protons increase, the atomic mass should increase, however if there are fewer neutrons it could decrease Mendeleev’s table worked because as the number of protons increase, the atomic mass should increase, however if there are fewer neutrons it could decrease 9

PERIODIC LAW PERIODIC LAW Periodic Law: physical and chemical properties of the elements are periodic functions of their atomic numbers Periodic Law: physical and chemical properties of the elements are periodic functions of their atomic numbers In other words, when the elements are arranged by their atomic numbers, you should see chemical and physical properties repeating themselves In other words, when the elements are arranged by their atomic numbers, you should see chemical and physical properties repeating themselves 10

ROWS Left to right – called periods Left to right – called periods Elements in the same periods show a pattern Elements in the same periods show a pattern As you move left to right, conductivity and reactivity change, and elements become less metallic As you move left to right, conductivity and reactivity change, and elements become less metallic 11

COLUMNS Top to bottom – called groups Top to bottom – called groups Elements in a group have similar chemical properties Elements in a group have similar chemical properties The elements in the same group (column) have the same number of valence electrons The elements in the same group (column) have the same number of valence electrons 12

EXPLORING THE PERIODIC TABLE Section 2 13

REMEMBER The periodic table is organized by atomic number The periodic table is organized by atomic number For a neutral atom, the number of protons equals the number of electrons For a neutral atom, the number of protons equals the number of electrons 14

VALENCE ELECTRONS The trends found in a periodic table are a result of electron arrangement, specifically, the number of valence electrons The trends found in a periodic table are a result of electron arrangement, specifically, the number of valence electrons Valence Electron: electrons in the outermost shell Valence Electron: electrons in the outermost shell 15

VALENCE ELECTRONS The group number of an element will tell you the number of valence electrons it has The group number of an element will tell you the number of valence electrons it has Group 1: 1 valence electron Group 1: 1 valence electron Group 2: 2 valence e - ’s Group 2: 2 valence e - ’s Skip the middle Skip the middle Group 13: 3 valence e - ’s Group 13: 3 valence e - ’s Groups 14-18: 4, 5, 6, 7, and 8 valence e - ’s respectively. Groups 14-18: 4, 5, 6, 7, and 8 valence e - ’s respectively. 16

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WHY DO WE CARE ABOUT ELECTRONS? 18

ION A neutral, stable atom will have equal protons and electrons A neutral, stable atom will have equal protons and electrons When an atom gains/loses electron(s), the atom is no longer neutral and has a charge When an atom gains/loses electron(s), the atom is no longer neutral and has a charge It becomes an ion It becomes an ion Ion: a charged atom Ion: a charged atom 19

ION Ionization: When atoms EITHER gain or lose electrons Ionization: When atoms EITHER gain or lose electrons All atoms want to have 8 valence electrons in the outer shell – this would make their outer shell full All atoms want to have 8 valence electrons in the outer shell – this would make their outer shell full Elements that are really close to having 8 electrons, desperately want to get there, and tend to be the most reactive. Elements that are really close to having 8 electrons, desperately want to get there, and tend to be the most reactive. Elements that are already “full” are considered inert, they don’t react because they don’t need to gain or lose electrons Elements that are already “full” are considered inert, they don’t react because they don’t need to gain or lose electrons 20

LET’S RECALL LET’S RECALL Protons = positive charge Protons = positive charge Electrons = negative charge Electrons = negative charge p + # CANNOT change, but e - # can p + # CANNOT change, but e - # can So… So… If an atom GAINED electrons, would they be more positive, or more negative? If an atom GAINED electrons, would they be more positive, or more negative? If they LOST electrons? If they LOST electrons? 21

ION Cation: atoms that LOSE electrons, becoming more positive Cation: atoms that LOSE electrons, becoming more positive Elements in group 1 are cations! Elements in group 1 are cations! Anion: atoms that GAIN electrons, becoming more negative Anion: atoms that GAIN electrons, becoming more negative Elements in group 17 are anions! Elements in group 17 are anions! 22

LET’S PRACTICE Group 16Give Up? or Gain? Group 16Give Up? or Gain? Group 13Give Up? or Gain? Group 13Give Up? or Gain? Group 15Give Up? or Gain? Group 15Give Up? or Gain? Group 2Give Up? or Gain? Group 2Give Up? or Gain? Group 1Give Up? or Gain? Group 1Give Up? or Gain? Group 17Give Up? or Gain? Group 17Give Up? or Gain? 23

ION How do we know if an atom is an ion? How do we know if an atom is an ion? Cations have a +, and anions have a – Cations have a +, and anions have a – If an atom has gained 3 electrons If an atom has gained 3 electrons It has 3 MORE negative particles than positive particles, it is more negative = Al 3- It has 3 MORE negative particles than positive particles, it is more negative = Al 3- If an atom has lost 3 electrons If an atom has lost 3 electrons It has 3 LESS negative particles than positive particles, it is more positive = Al 3+ It has 3 LESS negative particles than positive particles, it is more positive = Al 3+ 24

THE PERIODIC TABLE It is divided into three major categories It is divided into three major categories Metals Metals Nonmetals Nonmetals Metalloids (semiconductors) Metalloids (semiconductors) These categories are based on general properties and are further broken down into families These categories are based on general properties and are further broken down into families 25

Metals are left of the “staircase” Metals are left of the “staircase” Nonmetals are to the right Nonmetals are to the right Metalloids share properties of both Metalloids share properties of both 26

METALS Most elements are metals Most elements are metals Like to give up their valence electrons Like to give up their valence electrons Physical properties Physical properties high luster (shiny), conductive (heat and electricity), malleable (bendable), ductile (stretchable), high density, high melting point high luster (shiny), conductive (heat and electricity), malleable (bendable), ductile (stretchable), high density, high melting point All except Hg are solids at room temperature All except Hg are solids at room temperature Chemical properties Chemical properties Most will react with oxygen Most will react with oxygen 27

NONMETALS Like to gain electrons Like to gain electrons Physical properties Physical properties dull, don’t conduct, brittle, low density, low melting points dull, don’t conduct, brittle, low density, low melting points Like ashes (mainly carbon), can be solid, liquid or gas at room temperature depending on the element. Like ashes (mainly carbon), can be solid, liquid or gas at room temperature depending on the element. 28

METALLOIDS (SEMICONDUCTORS) Share properties of both metals and nonmetals Share properties of both metals and nonmetals Can be shiny or dull, conduct ok, ductile and malleable or brittle Can be shiny or dull, conduct ok, ductile and malleable or brittle These elements have become really important because of the computer revolution These elements have become really important because of the computer revolution Computer chips are made out of semiconductors (normally Si) Computer chips are made out of semiconductors (normally Si) By position Al is a metalloid, but its properties make it a light metal By position Al is a metalloid, but its properties make it a light metal 29

FAMILIES OF ELEMENTS Section 3 30

FAMILIES Families of elements have similar properties because they have the same number of valence electrons Families of elements have similar properties because they have the same number of valence electrons 31

METALS Alkali Metals, Alkaline-Earth Metals, Transition Metals 32

ALKALI METALS Group 1 (excluding H), 1 valence e - Group 1 (excluding H), 1 valence e - Very reactive, especially with water Very reactive, especially with water Soft, shiny white metals (can be cut with a knife!) Soft, shiny white metals (can be cut with a knife!) Low density (Li, Na, and K float in water) Low density (Li, Na, and K float in water) 33

HYDROGEN Hydrogen is in group 1 but is not an alkali metal, because it is only 1 proton and 1 electron (no neutrons) Hydrogen is in group 1 but is not an alkali metal, because it is only 1 proton and 1 electron (no neutrons) Its properties are closer to a nonmetals than to a metal Its properties are closer to a nonmetals than to a metal it is a colorless, odorless, explosive gas with oxygen it is a colorless, odorless, explosive gas with oxygen 34

ALKALINE-EARTH METALS Group 2, 2 valence e - Group 2, 2 valence e - Silver colored, more dense metals Silver colored, more dense metals Not as reactive as alkali metals, but still very reactive. Not as reactive as alkali metals, but still very reactive. Magnesium is used in flash bulbs Magnesium is used in flash bulbs 35

TRANSITION METALS Groups 3-12, 1 or 2 valence e - Groups 3-12, 1 or 2 valence e - Most are silver in color and somewhat reactive Most are silver in color and somewhat reactive These are most metals you are familiar with These are most metals you are familiar with iron, gold, copper, zinc and nickel iron, gold, copper, zinc and nickel Since they are not that reactive they have more everyday uses. Since they are not that reactive they have more everyday uses. 36

TRANSITION METALS Two bottom rows are the Lanthanide and Actinide series, sometimes called innertransition metals Two bottom rows are the Lanthanide and Actinide series, sometimes called innertransition metals Lanthanide: also called rare- earth metals Lanthanide: also called rare- earth metals Actinide: very radioactive and not easily found in nature Actinide: very radioactive and not easily found in nature 37

NONMETALS Halogens, Noble Gases 38

HALOGENS Group 17, 7 valence e - Group 17, 7 valence e - All nonmetals (can be solid, liquid or gas) All nonmetals (can be solid, liquid or gas) Extremely reactive with alkali metals Extremely reactive with alkali metals “Chlorine” added to pools as a disinfectant is a compound containing Chlorine, by itself chlorine is a green gas “Chlorine” added to pools as a disinfectant is a compound containing Chlorine, by itself chlorine is a green gas 39

NOBLE GASES Group 18, 8 valence e - ’s (except Helium) Group 18, 8 valence e - ’s (except Helium) Full outer shell of electrons Full outer shell of electrons All are gases and extremely non-reactive (inert) and found in the atmosphere All are gases and extremely non-reactive (inert) and found in the atmosphere “Neon” lights contain a variety of Noble Gases “Neon” lights contain a variety of Noble Gases 40

OTHER NONMETALS AND METALLOIDS Groups contain both nonmetals and metalloids Groups contain both nonmetals and metalloids Nonmetals: Oxygen, Nitrogen, Carbon, Sulfur, Phosphorus, and Selenium Nonmetals: Oxygen, Nitrogen, Carbon, Sulfur, Phosphorus, and Selenium Metalloids: Boron, Silicon, Germanium, Arsenic Antimony, and Terellium Metalloids: Boron, Silicon, Germanium, Arsenic Antimony, and Terellium The group is named by the first element in the column The group is named by the first element in the column 41

BORON GROUP Group 13, 3 valence e - Group 13, 3 valence e - All are solids at room temperature All are solids at room temperature Aluminum is the most common and is actually the most abundant element on the planet. Aluminum is the most common and is actually the most abundant element on the planet. 42

CARBON GROUP Group 14, 4 valence e - Group 14, 4 valence e - All are solids All are solids Pure carbon can be diamonds, soot (ashes), or graphite, silicon and germanium are used for computer chips, and tin and lead are common metals Pure carbon can be diamonds, soot (ashes), or graphite, silicon and germanium are used for computer chips, and tin and lead are common metals 43

NITROGEN GROUP Group 15, 5 valence e - Group 15, 5 valence e - All but nitrogen are solids, which makes up 78% of the air All but nitrogen are solids, which makes up 78% of the air Phosphorus is in several compounds (soaps) and Arsenic is a well known poison Phosphorus is in several compounds (soaps) and Arsenic is a well known poison 44

OXYGEN GROUP Group 16, 6 valence e - ’s Group 16, 6 valence e - ’s Except oxygen, all are solid Except oxygen, all are solid Oxygen makes up 21% of the air and is necessary for things to burn Oxygen makes up 21% of the air and is necessary for things to burn 45

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