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Ch. 11.4 Notes---Atomic Properties and the Periodic Table Valence Electrons and Electron Dot Notations What are “valence electrons”? • • • outer most energy level These are the electrons in the _________-_______ (or shell). These are responsible for chemical bonding. All of the other electrons are called “core electrons”. p electrons only. s electrons and “___” They will be “___” Counting Valence Electrons • Group A # = number of valence electrons 2 e-’s) (only exception Helium = __ 2 e-’s Examples: Ca = __ • 5 e-’s Nitrogen = __ 2 d-block and f-block = ___valence e-’s 8 e-’s Argon = __ Drawing Valence Electrons • “Electron-dot notation”: Electrons will be represented as dots located around the symbol of the element in the pattern shown below. 4 7 3 8 X 6 Examples: Nitrogen = N 1 5 2 Hydrogen = H (important exception.... Helium =He ) Carbon’s Hybrid Orbital ↑↓ C …___ ↑ ___ 2s ↑↑ C …___ ↑ ___ ___ (Before) ___ (After: 4 covalent bonds available) 2p ↑ ___ ↑ ___ 2sp3 Practice Problem: Draw the electron dot notation for Carbon: C Valence Electrons On The Periodic Table 1 8 2 3 4 5 6 7 Sucktastic! Assume 2 Son of Sucktastic! Assume 2 The Development of the Periodic Table • Dmitri Mendeleev _________________________: constructed the 1st periodic table Features of Mendeleev’s Periodic Table • • • • blank _________ spaces for “missing elements”. Later when He left ______ these elements were discovered, he filled in the gaps. He arranged the elements in columns and rows according to their properties __________________. Elements with similar properties were in the same horizontal row. predict He was able to accurately ___________ the properties of the missing rows elements based on the properties of the elements in similar _______. atomic ___________. mass He ordered the elements by increasing __________ Mendeleev’s Periodic Table Features of the Modern Periodic Table • • • • • Moseley In 1913, Henry ______________ determined the atomic number, (# p+ of the elements. of ___), – He then arranged the elements in the periodic table by increasing number atomic ____________. – This switched the position of some elements. This is how the modern periodic table is arranged today. Seaborg rearranged the periodic table to include In 1942 Glenn T. ________ the 5f row. He won a Nobel Prize after publishing his new periodic table. Periods Horizontal Rows = ____________ or Series Groups Vertical Columns = ____________ or Families groups families have similar properties. Elements in the same _________/_________ Figure 11.35: Classification of elements as metals, nonmetals, and metalloids. Parts of the Periodic Table • left of the dark zig-zag line running Metals: located to the _______ f through the “p-block”. This includes the elements in the ___-block. Properties of Metals – shiny surface malleable (you can pound it into a flat sheet) – ______________ ductile – ______________ (you can draw it into a thin wire) conductors – good _______________ (heat/electricity travels through it easily) Parts of the Periodic Table • Nonmetals: located to the ___________ right of the dark zig-zag line. Properties of Nonmetals dull surface – _______ sulfur brittle – ______________ insulators – good _______________ (or poor conductors) • Metalliods: located on the border of the dark zig-zag line. Examples: Silicon & Germanium – Properties of Metalliods semiconductors (Used in computer chips) ___________________ Parts of the Periodic Table • • d-block metals: “_________________ transition metals” rare-earth metals” f-block metals: “Inner-transition metals” or “____________ Special Group/Family Names • Alkali metals” Group 1A: “_________ – React with _________ water to form a base • Group 2A: “________________ Alkaline-earth metals” – Compounds are used in batteries • Halogens Group 7A: “_________________” – Used in some light fixtures • Group 8A (or 0 or 18): “_______ Noble gases” – Don’t form compounds (_________) inert Parts of the Periodic Table Innertransition metals Parts of the Periodic Table Trends in the Periodic Table Atomic Size (Atomic Radius) (See Fig. 11.36) • increases Moving Down a Group= the size of the atoms ________________ – • more of electrons to higher and Why? You are adding ________ higher energy levels (farther and farther out.) decreases Moving Across a Period= the size generally ______________ – Why? You are adding more e- and p+ to the same energy attraction of opposite level. This causes more ______________ pulls the electron cloud inward. charges and it __________ Figure 11.36: Relative atomic sizes for selected atoms. Trends in the Periodic Table Atomic Size vs. Ion Size (See Figure 12.8) • removing e-’s. Cation = (___) + charged atom created by ___________ smaller – Cations are ______________ than the original atom. Metals generally form cations. – _____________ • adding − charged atom created by _____________ Anion = (___) e-’s. larger – Anions are ____________ than the original atom. Nonmetals – _______________ generally form anions. Trends in the Periodic Table Atomic Size vs. Ion Size Figure 12.8: Relative sizes of some ions and their parent atoms. picometers Trends in the Periodic Table Ionization Energy • • remove Ionization energy is the energy required to _______________ the outer most electron in an atom. decreases Moving Down a Group= _______________ (less energy is needed) – Why? You are trying to remove an electron that is farther and farther out (for larger and larger atoms). These e-’s attracted are not as ________________to the nucleus. – In general, the larger the atom, the ____ less attracted it is to its e-’s. Trends in the Periodic Table Ionization Energy • increases Moving Across a Period= generally ________________ – Why? Moving across a period takes us from metals to nonmetals. More ionization energy is needed for ______________ nonmetals compared to __________. metals cations it won’t take as – Also, since metals generally form _________, much energy to remove it’s outer most electron. – Remember that as you move across the period, the atoms get _________ smaller and therefore ______ more attracted to the electrons. First Ionization Energies Trends in the Periodic Table “Successive Ionization Energies” • “Successive Ionization Energies” means the energy required to 2nd or a _____ 3rd electron from an atom. remove a _____ more and ______ more – Removing more and more e-’s requires ______ energy. – Why? tightly _________ bound The remaining e-’s are more _________ to the nucleus. Trends in the Periodic Table Electronegativity (See Figure 12.4) • • 0 – 4.0 which Electronegativity is a relative value (from_________) compares how much an atom is attracted to the e-’s in a ____________ chemical bond. Moving Down a Group= generally ______________ (less decreases attraction) – Why? The bonded electron is farther and farther out. These e-’s will not be as attracted to the larger and larger atoms. Figure 12.4: Electronegativity values for selected elements. Trends in the Periodic Table Electronegativity • increases Moving Across a Period= generally _________________ – Why? Again, the atoms are getting ________ smaller so they are more attracted to the bonding electrons. _______ – Also, moving across a period takes us from metals to anions nonmetals. Since nonmetals generally form _________, they gain tend to __________ e-’s anyway, and this makes them highly ________________ attracted to e-’s when forming a chemical bond. Noble __________ gases – ___________ are not listed in Figure 12.4 since they do not ________ form _____________ compounds ! Determining the Ion Formed • Atoms try to achieve a ________ noble ______ gas configuration when forming an ion. (This makes them more stable.) – Locate the nearest noble gas and count how many “places” it is away, but remember that you can skip over the d-block!! – This amount will be the same as the # of e-’s either gained or lost by the atom when forming an ion. Practice Problem: How many electrons are gained or lost when forming an ion from the following elements? a) Magnesium: ____ 2 (gained or lost) b) Iodine: ____ 1 (gained or lost) 3 (gained or lost) c) Gallium:____ 3 (gained or lost) d) Boron:____ Practice Problems: 2) a) Draw the electron dot notation for a potassium atom. K b) Draw the electron dot notation for a potassium ion. [K+1] 3) a) Draw the electron dot notation for a sulfur atom. S b) Draw the electron dot notation for a sulfur ion. [S -2]