






Study with the several resources on Docsity
Earn points by helping other students or get them with a premium plan
Prepare for your exams
Study with the several resources on Docsity
Earn points to download
Earn points by helping other students or get them with a premium plan
Community
Ask the community for help and clear up your study doubts
Discover the best universities in your country according to Docsity users
Free resources
Download our free guides on studying techniques, anxiety management strategies, and thesis advice from Docsity tutors
An introduction to ionic and covalent bonds, their formation, and the properties of ionic and covalent compounds. It covers the concepts of ions, cations, anions, crystals, and the differences between polar and nonpolar covalent bonds. The document also includes exercises for drawing ionic bonds and writing Lewis dot diagrams for various elements and ions.
What you will learn
Typology: Lecture notes
1 / 11
This page cannot be seen from the preview
Don't miss anything!
Introduction to Ionic Bonds The forces that hold matter together are called chemical bonds. There are four major types of bonds. We need to learn in detail about these bonds and how they influence the properties of matter. The four major types of bonds are: I. Ionic Bonds III. Metallic Bonds II. Covalent Bonds IV. Intermolecular (van der Waals) forces Ionic Bonds The ionic bond is formed by the attraction between oppositely charged ions. Ionic bonds are formed between metals and nonmetals. Remember that metal atoms lose one or more valence electrons in order to achieve a stable electron arrangement. When a metal atom loses electrons it forms a positive ion or cation. When nonmetals react they gain one or more electrons to reach a stable electron arrangement. When a nonmetal atom gains one or more electrons it forms a negative ion or anion. The metal cations donate electrons to the nonmetal anions so they stick together in an ionic compound. This means that ionic bonds are formed by the complete transfer of one or more electrons. A structure with its particles arranged in a regular repeating pattern is called a crystal. Because opposite charges attract and like charges repel, the ions in an ionic compound stack up in a regular repeating pattern called a crystal lattice. The positive ions are pushed away from other positive ions and attracted to negative ions so this produces a regular arrangement of particles where each ion is surrounded by ions of the opposite charge. Each ion in the crystal has a strong electrical attraction to its oppositely charged neighbors so the whole crystal holds together as one giant unit. We have no individual molecules in ionic compounds, just the regular stacking of positive and negative ions.
Reviewing Lewis Dot Diagrams Write the Lewis Dot Diagrams for the following: helium atom: beryllium atom: beryllium ion: neon atom: aluminum atom: aluminum ion: magnesium atom: magnesium ion: sodium atom: sodium ion: Write the Lewis Dot Diagrams for: oxygen atom: oxide ion: chlorine atom: chloride ion: phosphorus atom: phosphide ion: How would you describe (in general) the Lewis Dot Diagram for: a) a cation? b) an anion? What type of bonding would you expect in a compound that contains a metal and a nonmetal?
Introduction to Covalent Bonds A covalent bond is formed between nonmetal atoms. The nonmetals are connected by a shared pair of valence electrons. Remember, nonmetals want to gain valence electrons to reach a stable arrangement. If there are no metal atoms around to give them electrons, nonmetal atoms share their valence electrons with other nonmetal atoms. Since the two atoms are using the same electrons they are stuck to each other in a neutral particle called a molecule. A molecule is a neutral particle of two or more atoms bonded to each other. Molecules may contain atoms of the same element such as N 2 , O 2 , and Cl 2 or they may contain atoms of different elements like H 2 O, NH 3 , or C 6 H 12 O 6. Therefore, covalent bonding is found in nonmetallic elements and in nonmetallic compounds. Covalent bonds are intramolecular forces ; that is, they are inside the molecule and hold the atoms together to make the molecule. Covalent bonds are strong bonds and it is difficult and requires a lot of energy to break a molecule apart into its atoms. However, since molecules are neutral one molecule does not have a strong electrical attraction for another molecule. The attractions between molecules are called intermolecular forces and these are weak forces. Covalent substances have low melting points and boiling points compared to ionic compounds or metals. At room temperature, covalent substances are gases, liquids or low melting point solids. They do not conduct electricity as solids or when molten and usually do not conduct when dissolved in water.
Polarity When atoms share valence electrons they do not always share them equally. Frequently one atom has a stronger attraction for the electrons than the other atom does. This uneven attraction causes the electrons to be held closer to one end of the bond than the other; we say this makes one end of the bond slightly positive and the other end of the bond slightly negative. A covalent bond with uneven sharing of the electrons is called a polar covalent bond. A bond in which the electrons are shared equally is called a nonpolar covalent bond.
Bonding Pictures Review Sheet Draw Lewis dot diagrams for the following compounds. Remember that you must check the difference in electronegativity—to identify the compound as polar or non- polar. a) water (H 2 O) b) potassium iodide (KI) c) nitrogen molecule (N 2 ) d) ammonia (NH 3 ) e) calcium iodide (CaI 2 ) f) phosphorous trichloride (PI 3 ) g) aluminum fluoride (AlF 3 ) h) carbon dioxide (CO 2 ) i) oxygen molecule (O 2 ) j) magnesium nitride (Mg 3 N 2 )
k) chlorine molecule (Cl 2 ) l) ethane (C 2 H 6 ) (carbons hook to each other with H’s all around) m) hydroxide ion [OH]-^1 n) sulfite ion [SO 2 ]-^2 o) ammonium ion [NH 4 ]+1^ p) sodium oxide (Na 2 O) q) sulfate ion [SO 4 ]-^2 r) calcium bromide (CaBr 2 ) s) methane (CH 4 ) t) sulfur dioxide (SO 2 )