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Chapter 6. Atomic Structure Hingham High School Mr. Clune. Development of the Periodic Table. mid-1800s, about 70 elements Dmitri Mendeleev – Russian chemist Arranged elements in order of increasing atomic mass Thus, the first “Periodic Table”. Dimitri Mendeleev.
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Chapter 6 Atomic Structure Hingham High School Mr. Clune
Development of the Periodic Table • mid-1800s, about 70 elements • Dmitri Mendeleev – Russian chemist • Arranged elements in order of increasing atomic mass • Thus, the first “Periodic Table”
Mendeleev • Left blanks for undiscovered elements • When discovered, good prediction • Problems or inconsistencies? • Co and Ni; Ar and K; Te and I
New way • Henry Moseley – British physicist • Arranged elements according to increasing atomic number • The arrangement today • Symbol, atomic number & mass
Periodic table • Horizontal rows = Period • There are 7 periods • Periodic law: • Vertical column = Group (or family) Similar physical & chemical prop. Identified by number & letter
Horizontal rows are called periods • There are 7 periods
Vertical columns called groups Elements are placed in columns by similar properties Also called families
Periodic Law When elements are arranged in order of increasing atomic number, there is a periodic repetition of their physical and chemical properties.
Groups of Elements The vertical columns in the Periodic Table. Elements in each group have similar properties.
Groups of Elements Example: Group 11 Copper Silver Gold
Metals • 80% of the elements • Good Conductor • Heat • Electricity • High luster or sheen • Reflect light
Metals • Ductile • (Pulled into wire) • Malleable • (Hammered into sheets)
Non-Metals • Non-Metals are not Metals • (Properties unlike Metals) • Bad Conductors • (Except Carbon) • Brittle • (Shatter)
Non-Metals • Most are Gases • Oxygen, Nitrogen, Hydrogen!! • Some are Solid • (Sulfur and Phosphorus) • Some are liquid • Bromine is a dark brown liquid.
Areas of the periodic table • Group A elements = representative elements • Wide range of phys & chem prop. • Metals: electrical conductors, have luster, ductile, malleable
Metalloids • Staircase separating Metals and Nonmetals • Properties similar to • Metals and Nonmetals • Sometimes acts like a metal. • Sometimes acts like a nonmetal.
Silicon • Pure Silicon - Nonmetal. • Bad Conductor !!! • Add Boron • Conducts • electricity • SemiConductor
Atomic Number • Electron • Configuration • Chemical Symbol • Name • Mass Number Squares in a Periodic Table Si 2 8 6 14 Silicon 28.086
Noble Gases Non- Metals Metalloids Alkali Metals Alkaline Earth Metals Metals Halogens Transition Elements
H 1 Li 3 Na 11 K 19 Rb 37 Cs 55 Fr 87 Group 1 – _s1 1s1 1s22s1 1s22s22p63s1 1s22s22p63s23p64s1 1s22s22p63s23p64s23d104p65s1 1s22s22p63s23p64s23d104p65s24d10 5p66s1 1s22s22p63s23p64s23d104p65s24d105p66s24f145d106p67s1
Group 18 – _p16 He 2 Ne 1s2 1s22s22p6 1s22s22p63s23p6 1s22s22p63s23p64s23d104p6 1s22s22p63s23p64s23d104p65s24d105p6 1s22s22p63s23p64s23d104p65s24d10 5p66s24f145d106p6 10 Ar 18 Kr 36 Xe 54 Rn 86
S- block s1 s2 • Alkali metals all end in s1 • Alkaline earth metals all end in s2 • really should include He, but it fits better later. • He has the properties of the noble gases.
d 10 Transition Metals -d block s1d5 s1d9 d1 d2 d3 d5 d6 d7 d8
The P-block p1 p2 p6 p3 p4 p5 B C N O F Ne
f6 f13 f1 f2 f3 f4 f5 f7 f8 f10 f12 f14 f11 f9 F - block • inner transition elements
1 2 3 4 5 6 7 • Each row (or period) is the energy level for s and p orbitals.
1 2 3 4 5 6 7 Transition Elements Inner Transition Elements
Atomic Size } • Atomic Radius = half the distance between two nuclei of a diatomic molecule. Radius
Trends in Atomic Size • Influenced by three factors: 1. Energy Level • Higher energy level is further away. 2. Charge on nucleus • More charge pulls electrons in closer. • 3. Shielding effect (blocking effect?)
Group Trends H • As we go down a group... • each atom has another energy level, • so the atoms get bigger. Li Na K Rb
Periodic Trends • As you go across a period, the radius gets smaller. • Electrons are in same energy level. • More nuclear charge. • Outermost electrons are closer. Na Mg Al Si P S Cl Ar
Size generally increases Trends in Atomic Size
Trends in Ionization Energy • The amount of energy required to completely remove an electron from a gaseous atom. • Removing one electron makes a 1+ ion. • The energy required to remove the first electron is called the first ionization energy.
Ionization • Ion – A charged atom. Gains or loses electrons • Cation – Ion with a positive charge Loses electron(s) • Anion – Ion with a negative charge Gains electrons - + Na e- Cl
Ionization Energy • The second ionization energy is the energy required to remove the second electron. • Always greater than first IE. • The third IE is the energy required to remove a third electron. • Greater than 1st or 2nd IE.
Symbol First Second Third 1312 2731 520 900 800 1086 1402 1314 1681 2080 H HeLi BeB C N O F Ne 5247 7297 1757 2430 2352 2857 3391 3375 3963 11810 14840 3569 4619 4577 5301 6045 6276
What determines IE • The greater the nuclear charge, the greater IE. • Greater distance from nucleus decreases IE • Filled and half-filled orbitals have lower energy, so achieving them is easier, lower IE.
Group trends • As you go down a group, first IE decreases because... • The electron is further away.
Periodic trends • All the atoms in the same period have the same energy level. • But, increasing nuclear charge • So IE generally increases from left to right.
Energy generally increases Trends in Ionization Energy
Trends in Ionic Size • Cations form by losing electrons. • Cations are smaller that the atom they come from. • Metals form cations. • Cations of representative elements have noble gas configuration.
Ionic size • Anions form by gaining electrons. • Anions are bigger that the atom they come from. • Nonmetals form anions. • Anions of representative elements have noble gas configuration.
Group trends • Adding energy level • Ions get bigger as you go down. Li1+ Na1+ K1+ Rb1+ Cs1+
Periodic Trends • Across the period, nuclear charge increases so they get smaller. • Energy level changes between anions and cations. N3- O2- F1- B3+ Li1+ C4+ Be2+