2 Gain or Loss of Electrons Atomslose or gain to meet a standard— stability.Ioncharged particle because it now has either more or fewer electrons than protons.positive and negative charges are not balancedelectric forces hold compounds together
3 Gain or Loss of Electrons Common compoundsmade by the loss and gain of just one electron.some examplessodium chloride, commonly known as table salt;sodium fluoride, an anticavity ingredient in some toothpastes;potassium iodide, an ingredient in iodized salt
4 A Bond Forms Potassium Compound with iodine has one electron in its outer level.Compound with iodinepotassium loses one electron from its fourth level, and the third level becomes a complete outer level.
5 A Bond Forms Potassium atom The 1+ charge has become an ion the atom becomes positively charged because there is one electron less in the atom than there are protons in the nucleusThe 1+ chargeshown as a superscript written after the element’s symbol, K+ , to indicate its charge.
6 A Bond Forms The iodine atom undergoes change has seven electrons in its outer energy leveliodide atom gains an electron, leaving its outer energy level with eight electrons.
7 A Bond FormsIodineno longer neutral because it gained an extra negative particle.charge of 1− and is called an iodide ion, written as I−.
8 A Bond FormsNotice that the resulting compound has a neutral charge because the positive and negative charges of the ions cancel each other
9 The Ionic Bond Ionic bond force of attraction between the opposite charges of the ions in an ionic compounda transfer of electrons takes place.one or more elements must gain an equal number of electrons to maintain the neutral charge of the compound.
10 The Ionic Bond Magnesium chloride MgCl2, is another example of ionic bonding.magnesium reacts with chlorine, magnesium atom loses two electrons and becomes a positively charged ion, Mg2+.
11 The Ionic Bond Two chlorine atoms gain one electron each and become negatively charged chloride ions, Cl −
12 Zero Net Charge The result of this bond is a neutral compound. The compound as a whole is neutral because the sum of the charges on the ions is zero.
13 Zero Net Charge Ionic compound, electrons are shifted to the other atoms,the overall number of protons and electrons of the combined atoms remains equal and unchanged.Ionic bonds usually are formed by bonding between metals and nonmetals.
14 Sharing Electrons Nonmetals Group 4 unlikely to lose or gain electrons.Group 4four electrons in their outer levels.would have to either gain or lose four electrons in order to have a stable outer levelloss of this many electrons takes a great deal of energy
15 Sharing Electrons Covalent bond share electrons particle forms is a molecule.
16 Single Covalent Bonds Single covalent bond Water molecule Results made up of two shared electrons.Water moleculecontains two single bonds.in each bond, a hydrogen atom contributes one electron to the bond and the oxygen atom contributes the other.Resultsis a stable outer energy level for each atom in the molecule.
17 Multiple Bonds Covalent bond can contain more than one pair of electrons.nitrogen (N2).
18 Multiple Bonds Nitrogen atom has five electrons in its outer energy levelneeds to gain three electrons to become stable.It does this by sharing its three electrons with another nitrogen atom.
19 Multiple Bonds Each nitrogen atom contributes three electrons to the bond, the bond contains six electrons, or three pairs of electrons.each pair represents a bond.three pairs of electrons represent three bonds, or a triple bond.
20 Unequal Sharing Electrons not always shared equally between atoms in a covalent bond.elements close together in the upper right-hand corner of the periodic table.strength of the attraction to electrons related to the size of the atomcharge of the nucleus,total number of electrons the atom contains.
21 Unequal Sharing Strength of attraction how far away from the nucleus the electron being shared is.strength of attraction has to do with the size of the positive charge in the nucleus.
22 Unequal Sharing Unequal sharing Chlorine atoms found in a molecule of hydrogen chloride, HCl.Chlorine atomsstronger attraction for electrons than hydrogen atoms do.
23 Unequal Sharing Electrons shared Polar molecule spend more time near the chlorine atom than near the hydrogen atom.Polar moleculecharge is balanced but not equally distributedslightly positive end and a slightly negative endwater
24 Polar or Nonpolar? Nonpolar molecule electrons are shared equally in bonds.does not have oppositely charged ends.molecules made from two identical atoms or molecules that are symmetric, such as CCl4.
25 The Ionic Bond Attraction between 2 oppositely charged ions Ions - charged atomsformed by transferring e- from a metal to a nonmetal
26 Covalent Bond Attraction between neutral atoms formed by sharing e- between two nonmetals
27 Covalent Bond Nonpolar Covalent Bond e- are shared equally usually identical atoms
28 + - Covalent Bond Polar Covalent Bond e- are shared unequally between 2 different atomsresults in partial opposite charges+-
30 Comparison Chart IONIC COVALENT transferred from metal to nonmetal shared between nonmetalsElectronsMeltingPointhighlowSoluble inWateryesusually notUsual stateat room tempSolidsLiquid or GasSmallest ParticleMoleculesIons