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6.1 Ionic Bonding.  If highest energy level of an atom is filled with e-, the atom is stable and not likely to react  Chemical properties of an element.

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Presentation on theme: "6.1 Ionic Bonding.  If highest energy level of an atom is filled with e-, the atom is stable and not likely to react  Chemical properties of an element."— Presentation transcript:

1 6.1 Ionic Bonding

2  If highest energy level of an atom is filled with e-, the atom is stable and not likely to react  Chemical properties of an element depend on the number of valence electrons  Electron (Lewis) dot diagram = model in which each dot represents a valence electron

3 Highest energy level of a noble gas atom is completely filled Noble gases have stable electron configurations with 8 valence electrons (two electrons in helium). Elements tend to react to get electron configurations similar to noble gases

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5  Elements can get a stable electron configuration by transferring of electrons  Ex: A chlorine atom has one electron fewer than an argon atom, adding one electron would give chlorine a stable configuration Ex: A sodium atom has one more electron than a neon atom, removing one electron would give sodium a stable configuration.

6  When sodium reacts with chlorine, an electron is transferred from sodium atom to chlorine atom  Each atom ends up with a more stable electron arrangement than it had before transfer

7  Electron moves from Na to CL

8  Ionic Bonds = transfer of electrons  When an atom gains or loses an electron, the number of protons does not equal number of electrons  Charge on the atom is not balanced, and atom is not neutral  Ion = Atom that with positive or negative charge  Charge on an ion is represented by a plus or a minus sign  Negative charge = anion  Positive charge = cation

9  Ex: Ion that forms when a chlorine atom gains an electron has 17 protons and 18 electrons This ion has a charge of 1–. The symbol for the ion is written Cl 1–, or Cl – for short. Anions like the Cl – ion are named by using part of the element name plus the suffix –ide. Thus, Cl – is called a chloride ion.

10 Sodium ion has 11 protons and 10 electrons. The sodium ion has a charge of 1+. The symbol for the ion is written Na 1+, or Na + for short. An ion with a positive charge is a cation. A cation uses the element name, as in the sodium ion.

11 A particle with a negative charge will attract a particle with a positive charge Chemical bond = force that holds atoms or ions together as a unit Ionic bond =force that holds cations and anions together, forms when electrons are transferred from one atom to another (metal and non-metal)

12  Cations (+) form when electrons gain enough energy to escape from atoms  Energy allows electrons to overcome the attraction of the protons in the nucleus  Ionization energy = of energy used to remove an electrons  The lower the ionization energy, the easier it is to remove an electron from an atom

13 Ionization Energy

14  Compounds that contain ionic bonds are ionic compounds, can be represented by chemical formulas Chemical formula = shows what elements are in a compound, and how many of each Ex: Chemical formula for sodium chloride, NaCl, indicates one sodium ion for each chloride ion in sodium chloride

15  Compound made from only two elements is a binary compound  The names have a predictable pattern:  The name of the cation followed by the name of the anion.  Examples: sodium chloride

16  Formula of an ionic compound describes the ratio of the ions in the compound  2 different compounds of copper and oxygen are below  Has to be at least two names to distinguish red copper oxide from black copper oxide.

17  Polyatomic ion = covalently bonded group of atoms that has a positive or negative charge  Most simple polyatomic ions are anions

18 What is the chemical formula for magnesium chloride? Ionic Compounds

19 What is the chemical formula for magnesium chloride? Ionic Compounds MgCl 2

20 1. Write the name of the metal first and then the nonmetal. 2. Add an -ide ending to the non-metal 3. Use Roman Numerals to indicate charge on a transition metal  Ionic compounds involving polyatomic ions follow the same basic rule: 1. Write the name of the metal first, 2. Then the name of the polyatomic anions

21 Section 6.2 Covalent Bonds

22  Sharing of valence electrons  Non-metal and Non-metal  Attraction between shared electrons and the protons in each nucleus hold the atoms together in a covalent bond

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25  When two atoms share one pair of electrons, the bond is called a single bond  Hydrogen atom has one electron, if had two electrons, it would have the same electron configuration as a helium atom  Two hydrogen atoms can achieve a stable electron configuration by sharing their electrons and forming a covalent bond

26  Molecule = neutral group of atoms that are joined together by one or more covalent bonds  Many nonmetal elements exist as diatomic molecules  Diatomic means “two atoms”

27 Br-I-N-Cl-H-O-F Brinclhof Sounds like a German name. There’s also: I Brought Clothes For Our New Hamster … either way…

28 Bromine: Iodine: Nitrogen: Chlorine: Hydrogen: Oxygen: Fluorine:

29  2 pairs of electrons shared = double bond  3 pairs of electrons shared = triple bond  Nitrogen has five valence electrons.  When the atoms in a nitrogen molecule (N 2 ) share three pairs of electrons, each atom has eight valence electrons  Each pair of shared electrons is represented by a long dash in the structural formula N  N

30  Polar covalent bond = atom with the greater attraction for electrons has a partial negative charge  Other atom has a partial positive charge  Happens because the e- are closer to one atom than the other (one atom attracts e- more)  Type of atoms in a molecule and its shape are factors that determine whether a molecule is polar or nonpolar

31  Except for noble gases, elements on the right of the periodic table tend to have a greater attraction for electrons than elements on the left  Elements at the top of a group tend to have a greater attraction for electrons than elements at the bottom of a group have.

32  Covalent bonds= atoms attract electrons equally and are shared equally

33  Attractions between polar molecules are stronger than attractions between nonpolar molecules  Bonds between polar molecule are stronger than non polar

34  Prefixes tell you how many of each atom you have  Prefix goes in front of the element name  Mono- 1  Di -2  Tri – 3  Tetra -4  Penta – 5  Hexa – 6  Hepta – 7

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