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Types of Bonds. Chemical Bonds. A chemical bond is when atoms gain, lose or share electrons and an attraction forms that pulls the atoms together to make a compound. Ionic Bonding. Have you ever had a sports drink that had electrolytes?
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Chemical Bonds A chemical bond is when atoms gain, lose or share electrons and an attraction forms that pulls the atoms together to make a compound.
Ionic Bonding Have you ever had a sports drink that had electrolytes? Electrolytes are ions that our bodies use, such as Na+ (Sodium) and K+ (Potassium). Take out a piece of paper. Draw Lewis structures for Potassium and Iodine. Then draw their ions.
Ionic Bonding K I K I + -
Patterns What groups are Potassium and Iodine in on the periodic table? What charges do their ions have? What about elements in the same groups (i.e Sodium and Chlorine)?
Ionic Bonding The opposite charges of K+ and I- are attracted to each other, so they come together to form KI (potassium iodide). The resulting compound is neutral. 1- and 1+ is neutral the same way that +1-1=0 An ionic bond is the force of attraction between ions of opposite charges in an ionic compound.
Ionic Bonding Let’s look at Magnesium Chloride. Draw Lewis structures for atoms of Magnesium and Chlorine, then draw their ions.
Ionic Bonding Mg Cl How many electrons would each lose or gain? What are the resulting charges Mg2+ Cl -
Patterns What do you have to subtract from 2 to get 0? How many Chloride atoms bond to Magnesium to make a neutral compound? Mg2+ and Cl- would still have a charge of 1+ (+2-1=+1) Mg2+ and 2Cl- ( Cl- and Mg2+ and Cl-) would have a neutral charge. (-1+2-1=0) making MgCl2
Covalent Bonds-Word Patterns Look at the word covalent. Let’s break it down. Co- to share like co-sign, cooperate, co-president, coed Valent for valence electrons, so . . . Covalent bonds are when atoms share valence electrons (outer shell)
Covalent Bonding A molecule is a neutral particle that forms as a result of electron sharing. Remember water It has two single covalent bonds Each atom contributes one electron to the bond Like a handshake, one hand from each person (two hands total) makes one bond H O H
Covalent Bonding Atoms can also form double and triple bonds. Draw a Lewis structure for Nitrogen. N + N = N N Each atom contributes 3 electrons to completer each other’s shell (8 electrons), forming a triple bond. N2
Patterns Review What are two things compounds require to be stable? Outer electron shells of the atoms are filled (usually 8 is the magic number). The resulting compounds are neutral.
Polar and Nonpolar Covalent Bonds Like a tug-of-war, sometimes atoms that share electrons don’t share them equally. Like a larger stronger magnet, a larger stronger nucleus attracts electrons more than a smaller nucleus with fewer protons. Hydrochloric acid (HCl) is an example. Take a look at your periodic table.
Polar Covalent Bond How many protons does Chlorine have? How many protons in Hydrogen? Since Chlorine hogs the electrons, its side is more negatively charged. Cl H To represent the impartial charges we use the Greek symbol delta.δ δ- δ+
Nonpolar In molecules where both atoms are the same, like N2, the electrons are equally shared, and the molecule is nonpolar. Molecules that are symmetrical are also nonpolar.
Covalent and Ionic Properties Salt and sugar look very similar but have different properties (think of the taste!). Salt is Ionic Compound. Sugar is a Covalent Compound. Carefully, look at the table on the next slide.
