Chapters 7&8 – Flashcards
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| How do you find the amount of valence electrons in an atom? |
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| Look at the group number |
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| Atoms of which elements tend to gain electrons? Atoms of which elements tend to loose electrons? |
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| Metals tend to gain elements. Nonmetals tend to loose |
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| How are cations formed? |
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| An atoms loss of valence electrons forms a cation |
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| How are anions formend? |
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| The gain of negitively charged electrons by a neutral atom |
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| Valence electrons |
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| The electrons in the highest occupied energy level of an element's atoms |
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| Electron dot structures |
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| Diagrams that show valence electrons as dots. |
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| Octect Rule |
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| Atoms of metals tend to lose their valence electrons, leaving a complete octet in the next lowest energy level. Atoms of some nonmetals tend to gain electrons or to share electrons with another nonmetal to achieve a complete octet. |
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| Halide Ions |
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| Ions that are produced when atoms of chlorine and other halogens gain electrons |
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| What is the electrical charge of an ionic compound? |
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| Electrically neutral |
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| What are three properties of ionic compounds? |
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| -Crystaline structures at room temp -Have high melting points -Can conduct electricty when melted or in water |
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| Ionic Compounds |
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| Compounds composed of cations an anions. |
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| Ionic Bonds |
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| The electrostatic forces holding ions together in ionic compounds |
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| Formula Unit |
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| Lowest whole number ratio of ions in an ionic compound |
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| Coordination Number |
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| the number of ions of opposite charge that surround the ion in a crystal. |
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| How can you model the valence electrons of metal atoms? |
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| As a sea of electrons |
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| How are metal ions arranged? |
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| In very compact and orderly patterns. |
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| Why are alloys important? |
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| Their properties are often superior to those of their component elements |
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| Alloys |
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| Mixtures composed of two or more elements, at least one of which is a metal. |
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| Metallic Bonds |
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| Consist of the attraction of the free-floating valence electrons for the positively charged metal ions. |
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| How are the melting points and boiling points of molecular compounds different from those of ionic compounds? |
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| Molecular compounds tend to have relatively lower melting and boiling points than ionic compounds |
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| What information does a molecular formula provide? |
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| A molecular formula shows how many atoms of each element a molecule contains. |
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| Covalent Bond |
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| Atoms held together by sharing electrons |
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| Molecule |
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| Neutral group of atoms joined together by covalent bonds |
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| Diatomic Molecule |
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| Molecule consisting of two atoms |
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| What is the result of electron sharing in covalent bonds? |
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| In covalent bonds, electron sharing usually occurs so that atoms attain the electron configurations of noble gases. |
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| How do electron dot structures represent shared electrons? |
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| An electron dot structure such as H:H represents the shared pair of electrons of the covalent bond by two dots. |
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| How are coordinate covalent bonds different from other covalent bonds? |
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| In a coordinate covalent bond, the shared electron pair comes from one of the bonding atoms. |
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| How is the strength of a covalent bond related to its bond dissociation energy? |
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| A large bond dissociation energy corresponds to a strong covalent bond. |
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| How are oxygen atoms bonded in ozone? |
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| A hybrid, or mixture, of the extremes represented by the resonance forms |
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| What are some exceptions to the octet rule? |
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| The octet rule cannot be satisfied in molecules whose total number of valence electrons is an odd number. There are also molecules in which an atom has fewer, or more, than a complete octet of valence electrons. |
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| Single Covalent Bond |
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| Two atoms held together by sharing a pair of electrons. |
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| Structual Formula |
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| Represents the covalent bonds by dashes and shows the arrangement of covalently bonded atoms. |
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| Unshared Pair |
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| A pair of valence electrons that are not shared by atoms |
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| Double Covalent Bond |
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| A bond that involves two shared pairs of electrons. |
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| Coordinate Covalent Bond |
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| A covalent bond in which one atom contributes both bonding electrons. |
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| Bond Disassociation Energy |
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| The energy required to break the bond between two covalently bonded atoms. |
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| Resonance Structure |
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| A structure that occurs when it is possible to draw two or more valid electron dot structures that have the same number of electron pairs for a molecule or ion. |
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| How are atomic and molecular orbitals related? |
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| Just as an atomic orbital belongs to a particular atom, a molecular orbital belongs to a molecule as a whole. |
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| How does VSEPR theory help predict the shapes of molecules? |
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| According to VSEPR theory, the repulsion between electron pairs causes molecular shapes to adjust so that the valence-electron pairs stay as far apart as possible. |
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| In what ways is orbital hybridization useful in describing molecules? |
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| In what ways is orbital hybridization useful in describing molecules? |
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| Molecular Orbitals |
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| When two atoms combine, this model assumes that their atomic orbitals overlap |
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| Bonding Orbitals |
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| A molecular orbital that can be occupied by two electrons of a covalent bond |
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| Sigma Bond |
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| When two atomic orbitals combine to form a molecular orbital that is symmetrical around the axis connecting two atomic nuclei. |
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| Pi Bond |
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| The bonding electrons are most likely to be found in sausage-shaped regions above and below the bond axis of the bonded atoms. |
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| Tetrahedral Angle |
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| In this arrangement, all of the H—C—H angles are 109.5°. |
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| Hybridization |
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| Several atomic orbitals mix to form the same total number of equivalent hybrid orbitals |
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| How do electronegativity values determine the charge distribution in a polar bond? |
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| The more electronegative atom attracts electrons more strongly and gains a slightly negative charge. The less electronegative atom has a slightly positive charge. |
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| What happens to polar molecules between a pair of oppositely charged metal plates. |
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| When polar molecules are placed between oppositely charged plates, they tend to become oriented with respect to the positive and negative plates. |
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| How do intermolecular attractions compare with ionic and covalent bonds? |
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| Intermolecular attractions are weaker than either ionic or covalent bonds. |
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| Why do network solids have high melting points? |
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| Melting a network solid would require breaking covalent bonds throughout the solid |
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| Why do network solids have high melting points? |
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| Melting a network solid would require breaking covalent bonds throughout the solid |
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| Nonpolar Covalent Bond |
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| When the atoms in the bond pull equally (as occurs when identical atoms are bonded), the bonding electrons are shared equally |
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| Polar Covalent Bond |
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| Covalent bond between atoms in which the electrons are shared unequally. |
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| Polar Molecule |
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| One end of the molecule is slightly negative and the other end is slightly positive. |
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| Dipole |
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| A molecule that has two poles is called a dipolar molecule. |
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| van der Waals Forces |
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| The two weakest attractions between molecules. |
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| Dipole Interactions |
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| Occur when polar molecules are attracted to one another. |
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| Dispersion |
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| The weakest of all molecular interactions, are caused by the motion of electrons. |
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| Hydrogen Bonds |
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| Attractive forces in which a hydrogen covalently bonded to a very electronegative atom is also weakly bonded to an unshared electron pair of another electronegative atom. |
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| Network Solid |
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| Solids in which all of the atoms are covalently bonded to each other. |
