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Learning objectives:. After completing this unit of study, you should be able to : An element’s location on the periodic table gives an indication of its physical and chemical properties. Elements on the Periodic Table are arranged in order of increasing atomic number.
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Learning objectives: After completing this unit of study, you should be able to: • An element’s location on the periodic table gives an indication of its physical and chemical properties. • Elements on the Periodic Table are arranged in order of increasing atomic number. • Elements are classified as metals, nonmetals and metalloids based on their properties and location on the periodic table. • Groups 1, 2, and 13-18 have the same number of valence electrons in the group, and therefore have similar chemical properties. Helium is the exception to this. • Each group shows trends in atomic radius, ionic radius, Electronegativity, first ionization energy, and metallic and nonmetallic properties. • Each period shows trends in atomic radius, Electronegativity, first ionization energy, and metallic and nonmetallic properties. • When an element becomes an anion by gaining electrons, the radius increases. • When an element becomes a cation by losing electrons, the radius decreases. • Some elements exist as two or more forms in the same phase due to differences in molecular or crystal structures, and therefore have different chemical and physical properties. These are called Allotropes. Carbon has the allotropes coal, graphite, diamond, and fullerenes. Oxygen has the allotropes O2 & O3.
Learning Guide 1: P.T. Basics • Dimitri Mendeleev organized the 1st periodic table by atomic mass. • Mosley re-organized the periodic table by atomic number. • This was better because there are places on the periodic table that mass goes down, but atomic number ALWAYS INCREASES BY 1. • Modern Periodic Law states that elements are organized by atomic number, and properties are determined by number of valence electrons.
Learning Guide 1: P.T. Basics Atomic Mass Oxidation States (charge) Symbol Atomic Number Electron Configuration
Learning Guide 1: P.T. Basics 6. A PERIOD is a horizontal row on the periodic table. 7. All elements in a period have valence electrons in the same ring. 8. The number of valence electrons go up by one as you go cross a period.
Learning Guide 1: P.T. Basics 9. Metals are located to the left and below the staircase line. 10. Nonmetals are located to the right and above the staircase line. 11. Metalloids (Semimetals) are located bordering the staircase line.
Learning Guide 1: P.T. Basics 12. The majority of the elements are SOLID at room temperature. 13. There are 2 elements that are liquids at room temperature: Bromine (Br) & Mercury (Hg). 14. The gases at room temperature are : Hydrogen (H), Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), Radon (Rn), Flourine (F), Oxygen (O), Nitrogen (N), Chlorine (Cl)
Learning Guide 1: P.T. Basics 15. A GROUP is a vertical column on the periodic table. 16. Another name for a group is a family. 17. All elements of a group have the same number of valence electrons. 18. All members of a group have similar reactivity.
Learning Guide 2: M/NM/SM • Nonmetal ions are larger than the atoms from which they are formed from because they gain electrons. • Metal ions are smaller than the atoms from which they from because they lose electons.
Learning Guide 2: M/NM/SM 3. Transition metals are located in groups 3-12. 4,,The transition metals have multiple (more than one) oxidation states. 4. 2 unique characteristics are multiple oxidation states and colored solutions in water.
Learning Guide 2: M/NM/SM 5. Metalloids are elements that have properties of both metals and nonmetals. 6. Metalloids border the staircase line.
Learning Guide 2: M/NM/SM 7. Noble gases are found in group 18. 8. They are unique because they do not react with other elements (they are snobs).
Learning Guide 2: M/NM/SM 9. Allotope: elements that exist as two or more forms in the same phase due to differences in molecular or crystal structures, and therefore have different chemical and physical properties. 10. a. Carbon (C) has the allotropes coal, graphite, diamond, and fullerenes. b. Oxygenhas the allotropes O2 & O3. Phosphorus has 3 allotropes
Metal & Nonmetal LAB METALS NONMETALS Dull (not shiny) Can be solid or liquid or gas Hard & Brittle ( crushes to a powder easily) Does NOT conduct Does NOT react • Luster: shiny • Mostly solid • Soft: Malleable – can flatten easily Ductile – can be a wire • Conducts heat & electricity (Cu wire , Ag & Au jewelry) • Reactive ( bubbles w/ HCl, darkens w/ CuCl2)
Which elements that you tested were METALS? LIST: Support:
Which elements that you tested were NONMETALS? LIST: Support:
Which elements that you tested were METALLOIDS? LIST: Support:
Nuclear Charge • The charge of the nucleus • The number of protons = atomic number • Greater nuclear charge means greater attraction of nucleus on the electrons • Means smaller radius, harder to lose e- (IE) easier to gain e- (e-neg)
Shielding • Kernel electrons interfere with the nuclear attraction for valence electrons. • More energy levels mean that it is easier to remove an e- and harder to gain an e-, because protons are shielded by the kernel e- in between them.
Ionization Energy • The amount of energy needed to remove the outermost electron. • More IE = harder to remove an electron • Less IE = easier to remove an electron
Learning Guide 3: Trends in Groups & Families nuclear charge 4. As you go left to right across a period, nuclear charge increases, electrons are stronger attracted and more energy is required to remove them
Learning Guide 3: Trends in Groups & Families nuclear charge • 5. As you go top to bottom down a group, valence elevtrons are farther from the nuclesu and it is easierenergy is required to remove them
Atomic Radius DEF: ½ the distance between 2 atoms OR THE RADIUS OF AN ATOM
Learning Guide 3: Trends in Groups & Families 7. As you go left to right across a period atomic radius decreases. 8. As nuclear charge increases as you go left to right across a period, the number of protons increase, pulling tighter on electrons and making the radius smaller.
Learning Guide 3: Trends in Groups & Families 9. Shielding effect across a period is constant because balance electrons are in the same energy level in the same period. Li Be B C N O F Ne e- config:2-1 2-2 2-3 2-4 2-5 2-6 2-7 2-8 Across a period sheilding has NO EFFECT!!
Learning Guide 3: Trends in Groups & Families 10. As you go top to bottom down a group atomic radius increases. 11. The number of occupied energy levels increases as you go top to bottom down a group. 12. Shielding causes atomic size to INCREASE as atomic number increases down a group.
Learning Guide 3: Trends in Groups & Families 13. ION: a charged part of an atom, resulting from the loss or gain of an electron. 14. Ionic Radius: LOSS of electron ion is SMALLER than atom GAIN of electron ion is BIGGER than atom
Learning Guide 3: Trends in Groups & Families 15. Metals tend to lose electrons to form an ion with a radius that is smaller than the atom. 16. Nonmetals tend to gainelectrons to form an ion with a radius that is largerthan the atom.
Learning Guide 3: Trends in Groups & Families 17. Electronegativity: A measure of how easily an atom gain gain (attract) electrons. Bigger EN number: easier to gain LOOK ON REF. TABLE S!!!!!!!! 18. Flourine has highest EN value of 4.0 19. Francium has lowest EN of 0.7
Remember ionic radius??? • When an atom forms an ION that is POSITIVE, the IONIC RADIUS is LESS THAN ATOMIC RADIUS, because it LOSES ELECTRONS • When an atom forms an ION that is NEGATIVE, the IONIC RADIUS is BIGGER THAN ATOMIC RADIUS, because it GAINS ELECTRONS
Pg 14-17 notepacket: • Atomic Radius – distance from nucleus to valence electron • Ionization Energy: energy required to remove the outermost electron • Electronegativity – a measure of ability to gain an electron
Periodicity: • FOLLOWS A PATTERN • There are general trends in properties as you move left to right across a period. • There are general trends in properties as you move top to bottom down a group.
Periodic Trend in Number of Valence Electrons 1.) What is the trend in valence electron number as you go from left to right across any period on the table? 2.) What is the trend in the valence electron number as you go down any group from top to bottom? 3.) What is the trend in the number of energy levels as you go down any group from top to bottom? 4.) Use your answers to #2 & 3 to write a statement explaining the relationship between number of valence electrons and the number of energy levels.
