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3.1(1) How do the properties of compounds compare to the properties of the elements from which they are composed?
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3.1(1)The properties of compounds are generally very different from the elements that compose them. When two elements combine to form a compound, an entirely new substance results.
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3.2(1) What is a chemical bond?
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3.2(1)Chemical bonds, the forces that hold atoms together in compounds, arise from the interactions between nuclei and electrons in atoms.
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3.2(2) What is an ionic bond?
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3.2(2)An ionic bond occurs between a metal and a nonmetal. In an ionic bond, one or more electrons are transferred from one atom to another forming a cation and an anion. The two ions are then drawn together by the attraction between the opposite charges.
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3.2(3)What is a covalent bond?
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3.2(3)A covalent bond occurs between nonmetals only. In a covalent bond, one or more electrons are shared between two atoms. The atoms are held together by the attraction between their nuclei and the shared electrons.
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3.3 (1) Explain the different ways to represent compounds. Why are there so many?
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3.3(1) You can represent compounds using chemical formulae, which represent compounds by indicating the elements present in those compounds. You can also use molecular models, which portray the geometry of the molecules/compounds. The type of formula you use depends on how much info you have, and how much info you want to communicate.
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3.3 (2) What is the difference between an empirical formula and a molecular formula?
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3.3(2) An empirical formula gives the relative (reduced) number of atoms of each element in a compound, whereas a molecular formula gives the actual number of atoms of each element in a molecule of a compound. Ex: Molecular Formula: H2O2, Empirical Formula: HO
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3.3 (3) What is a structural formula?
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3.3(3) A structural formula uses lines to represent covalent bonds and shows how atoms in a molecule are bonded together. Ex: H2O2 is H -- O -- O -- H
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3.3(4) What is a ball-and-stick model?
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3.3(4) A ball-and-stick model represents atoms as balls and chemical bonds as sticks; how the two connect reflects a molecule's shape.
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3.3(5) What is a space-filling molecular model?
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3.3(5) A space-filling molecular model is similar to the ball-and stick model except atoms fill the space between each other - this is the best representation of a molecule scaled up.
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3.4(1) Define and provide an example for each of the following: atomic element, molecular element, ionic compound, and molecular compound.
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3.4(1)
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3.4(2) What is the formula unit?
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3.4(2) The formula unit is the smallest identifiable unit of an ionic compound; it is the smallest electrically neutral collection of ions.
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3.4(3) What is a polyatomic ion?
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3.4(3) A polyatomic ion is an ion composed of two or more atoms.
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