CP NT Ch. 7 & 9—Ionic Bonds & Compounds plus Naming Forming Chemical Bonds Compounds (Review) • Remember compounds are ____________ or more different elements that combine chemically • Can be broken down by __________________ means • Have properties ________________________ from those of its component element • Thousands of compounds exist Chemical Bonds • A chemical bond is a force that holds ____________ atoms together • Chemical bonds usually only involve ____________________ electrons Chemical Bonds Ionic bonds Covalent bonds __________________ __________________ electrons electrons Valence Electrons • Valence electrons are electrons in the _____________________ occupied s and p energy level. • The number of valence electrons largely _____________________ the chemical properties of an element. • To find the number of valence electrons in a representative (group A) element, simply look at its ____________________ number. Lewis dot diagram • Diagrams that show valence electrons as dots Why do elements react? • Noble Gases are chemically stable because they have ______________ valence electrons called an octet • Elements tend to react in order to __________________ a full octet or “eight is great” (gain stability) • Octet rule –when forming compounds, atoms tend to achieve the stable electron structure of a ________________________ • YouTube Video: Brainiac Alkali Metals 1 Formation of Positive Ions-­‐Cations • A cation is an atom or group of atoms with a positive charge because of a __________ of electrons. Ca “+” ion • ___________ valence electrons • _______________ only form cations • Reactivity of metals is based on the ease in which they ____________ a valence electron to achieve a stable octet. Electron Configuration of Positive Ions-­‐Cations • A sodium metal ion has the electron configuration of the noble gas neon; Ne: 8 is great! Na atom Na 1s22s22p63s1 Na ion (lost 1 electron) Na+ 1s22s22p6 Ne atom (noble gas) Ne 1s22s22p6 Cation Charges • Group 1A loses 1 electron, making a _____ ion • Group 2A loses 2 electrons, making a ______ ion • Group 3A loses 3 electrons, making a _______ ion Formation of Negative Ions-­‐Anions • An anion is a negative atom or group of atoms that ___________ electrons • _______________________ tend to gain electrons Electron Configuration of Negative Ions-­‐”Anions” • Cl ion has the noble gas configuration of argon. 8 is great! Cl atom Cl 1s22s22p63s23p5 Cl ion (gain 1 electron) Cl-­‐ 1s22s22p63s23p6 Ar atom Ar 1s22s22p63s23p6 Anion Charges • 5A tend to gain 3 electrons, making a _______ ion • 6A tend to gain 2 electrons, making a _______ ion • 7A tend to gain 1 electron, making a _______ ion • The ion produced when atoms of halogens (group 7A) gain electrons are called ________________ ions 2 Formation and Nature of Ionic Bonds Ionic Bond • Ionic bond – the _____________________________ force that holds ions together in an ionic compound • ______________________________ force – like charges repel, opposite charges attract Formation of an Ionic Bond 1. Electrons are ______________________ from a metal to a nonmetal 2. The transfer produces a cation and ______________. 3. Ions are held together by ____________________ _______________ 4. Results in a very _______________ crystal lattice structure. Ionic Compounds • Compound ______________________ of cations and anions • Usually a metal and nonmetal • Overall _____________________ charge (zero) • Held together by ______________ bonds • A.K.A.: __________ Binary Compounds • Has just ________ different elements • A metallic cation combines with a nonmetallic anion • Example • -­‐MgO • -­‐Not CaSO4, why? Formula Units • A chemical formula shows the kinds and numbers of atoms in the ___________________ representative unit of a substance • Sodium chloride è NaCl • A formula unit is the lowest whole-­‐number ______________ of ions in an ionic compound Example 1 Atoms Cation Anion Ratio Formula Unit Mg and O Mg O Na and O Na O Example 2 • Predict the compound formed when magnesium and nitrogen combine. 1. Start with the atoms 2. Write their ions 3. Crisscross charges to get neutral compound 3 4. Write formula unit (make sure to reduce to lowest whole number ratio) Properties of Ionic Compounds • Strong bonds • _____________ melting and boiling points • ___________ at room temperature • Hard, rigid, and ____________ • When dissolved in water or melted it can conduct an __________________ current Electrolyte • Definition: A substance that conducts an electric current when it is _____________________ in water. • When an ionic compound dissolves in solution it breaks up into its ______________________ ions. This enables it to conduct a current because the ions move around. • Gatorade has electrolytes. It has _____________ dissolved in water for your body to conduct electrical currents. Crystal Lattice • _____________ of ionic compounds • Repeating __________ pattern • Large _________________________ forces result in a very stable structure Names and Formulas for Ionic Compounds Types of ions • ________________________ ion ion with ___________ atom • Mg2+ magnesium ion • Cl-­‐ chloride ion • __________________________ ion ion with ____________ than one atom • NH4+ ammonium • NO3-­‐ nitrate Naming Ca”+”ions • Monatomic cation name ____________ the same 4 Sodium, Na goes to _________________ ion, Na+ Calcium, Ca goes to ________________ ion, Ca 2+ • Polyatomic cation -­‐ look up in chart NH4+ ammonium Naming Anions • The name ________________ in a monatomic anion • The ending for a monatomic anion is ______ide (like a bride changes her last name) – chlorine, Cl goes to _________________ ion, Cl-­‐ – Fluorine, F goes to _________________ ion, F-­‐ • Polyatomic anion look up in chart – OH-­‐ hydroxide – SO42-­‐ sulfate Question Time Given the neutral atom, give the charge and name of the monatomic ion that will form. (Look at periodic table group numbers for help.) For polyatomic ions (6-­‐10, look up in chart). 1. Na 6. NH4+ 2. Cl 7. OH-­‐ 3. Mg 8. SO32-­‐ 4. S 9. SO42-­‐ 5. P 10. CN-­‐ Naming ionic compounds • Name the cation first and then the anion second (+ then -­‐) • Example: CsF – Monatomic cations use the element name – Cs+ = ___________________ ion – Monatomic anions – change the ending to ide – F -­‐ = ________________ ion • Name: _______________________ Will these form an Ionic Compound? If so what will the compound name be? 1. Mg, Al 2. Al, S 3. Mg, O 4. Na, N 5. C, S Formula Unit • Formula Unit—the ____________________ ratio of ions in an ionic compound 5 •
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NaCl versus Na2Cl2 Correct: Sodium Chloride NaCl What will the formula be? • In ionic compounds, we must ___________________charges to form a _____________________ compound. • To do that, we “crisscross the charges” similar to finding the least common denominator in a fraction. • Ex: Ca and N à form Ca2+ and N3-­‐ ions à Ca3N2 Formula Unit with Polyatomic ions • Sometimes you will need to use _____________ than one polyatomic ion to balance a charge. • If so, you need to put it in _______________________ (like a package) and use a subscript for the multiple number • Ex: Mg2+ and NO3-­‐ Transition Metal Ions • Metals form ________________ • Some transition metals only have __________ ionic charge • Ex: Silver (Ag+), Cadmium (Cd2+), Zinc (Zn2+) • Some transition metals can take on _____________ than one charge. • Ex: Copper (Cu+, Cu2+) • Charge is determined from the number of electrons __________ Naming Transition Metal Ions • If a transition metal has more than one charge, the charge is written as a __________________ numeral in parenthesis • Some metals need a middle name • Fe (iron) has more than one charge: 2+ and 3+ Fe2+ __________________ Fe3+ __________________ • If the transition metal only has one charge, no __________________ numeral is needed Naming Ionic Compounds with Transition Metals • Given: Fe2O3 First find the __________________ of the ions Then _____________ the cation followed by the anion Name: __________________ ___________________ Try this one: Fe3P2 Question Time • Name the charge on the transition metal: 1. Copper(II) nitrate 2. Gold(I) chromate • Name the compound: 6 1. FeO 2. Zn(OH)2 3. CoPO4 Metallic Bonds and Properties of Metals Metals • Metals are made up of closely packed ________________ surrounded by electrons, rather than neutral atoms of ions • Outer _______________ clouds of the metal ions overlap • Electron sea model – metal atoms in a solid contribute their ________________ electrons to form a “sea of electrons” • Delocalized electrons – Electrons that are free to _____________ in the “sea of electrons” Metallic Bond • Definition: The ___________________ of the delocalized electrons for the positively charged metal ions • Metal bonded to ________________ • Each ion is bonded to all _______________________ cations by the “sea” of valence electrons Properties of Metals • In general, metals have moderately ______________ melting and boiling points • _______________ conductors of heat and electricity • Electrons are free to move so transfer electrical charge/heat • Malleable and Ductile • Mobile electrons can easily be ____________ or _________________ past each other Structure of Metals • Metal atoms are arranged in very compact and orderly _____________________ • Metals that contain just one kind of atom are among the simplest forms of all _________________ solids Metal Alloys • Alloy is a mixture of __________ or more elements (at least one must be a metal) • Alloy’s have metallic properties often __________________to those of their component elements Bronze: copper + tin Steel: iron + carbon + other metals Sterling silver: silver + copper 7