Chem Vocab Unit 2 PDF

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Vocab for chem 1307 unit 2...

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Unit Study Guide 2: Elements and Compounds

Key Equations (2.1) average atomic weight =

∑

(exact mass)(fractional abundance)

all isotopes

Key Terms proton A positively charged subatomic particle found in the nucleus neutron An electrically neutral subatomic particle found in the nucleus electron atomic nucleus The core of an atom; made up of protons and neutrons atomic mass unit (u ) The unit of a scale of relative atomic masses of the elements;1 u = 1/12 of the mass of a carbon atom with six protons and six neutrons ion An atom or group of atoms that has lost or gained one or more electrons so that it is no longer electrically neutral cation An ion with a positive electrical charge anion An ion with a negative electric charge atomic number (Z ) The number of protons found in the nucleus of an atom of an element mass number (A ) The sum of the number of protons and neutrons in the nucleus of an atom of an element atomic symbol The one- or two-letter symbol that represents the element along with the atomic number, written as a subscript number, and the mass, written as a superscript number isotopes Atoms with the same atomic number but different mass numbers because of a difference in the number of neutrons atomic weight The average mass of an atom in a natural sample of the element periodic table of the elements https://ng.cengage.com/studycenter/index.html#/print/unitStudyGuides/MYJYOD921753099

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A table of elements organized by increasing atomic number groups The vertical columns in the periodic table periods The horizontal rows in the periodic table alkali metal Any of the metals in Group 1A of the periodic table halogen Any of the elements in Group 7A of the periodic table alkaline earth metal Any of the elements in Group 2A of the periodic table noble gas Any of the elements in Group 8A of the periodic table main-group elements An element in the A groups in the periodic table transition elements

d The elements in Groups 3B–2B (3–12) of the periodic table, or those elements whose atoms have partially filled orbitals in their neutral or cationic state lanthanides The series of elements between lanthanum and hafnium in the periodic table actinides The series of elements between actinium and rutherfordium in the periodic table metals An element characterized by a tendency to give up electrons and by good thermal and electrical conductivity nonmetals An element characterized by a lack of metallic properties metalloids An element with properties of both metals and nonmetals semimetals An element with properties of both metals and nonmetals allotropes Different forms of the same element that exist in the same physical state under the same conditions of temperature and pressure covalent compound A compound formed by atoms that are covalently bonded to each other molecular covalent compound A compound formed by the combination of atoms without significant ionic character network covalent compound A compound made up of a network of covalently bonded atoms https://ng.cengage.com/studycenter/index.html#/print/unitStudyGuides/MYJYOD921753099

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molecular formula A written formula that expresses the number of atoms of each type within one molecule of a compound empirical formula A molecular formula showing the simplest possible ratio of atoms in a molecule structural formula A variation of a molecular formula that expresses how the atoms in a compound are connected condensed structural formula A variation of a molecular formula that shows groups of atoms wedge-and-dash model A two-dimensional representation of a three-dimensional structure that can easily be drawn on paper, where bonds are represented by lines, wedges, or dashes ball-and-stick model A molecular model that shows atoms as colored spheres connected by sticks that represent covalent bonds space-filling model A representation of a molecule where interpenetrating spheres represent the relativeamount of space occupied by each atom in the molecule binary nonmetal A compound formed from two elements, both nonmetals inorganic acid An acid that produces the hydrogen ion H ( + ) when dissolved in water and that contains hydrogen and one or more nonmetals hydrocarbon A compound that contains only carbon and hydrogen oxoacids Groups of acids that differ only in the number of oxygen atoms ionic compound A compound formed by the combination of positive and negative ions monoatomic ion A single atom that has gained or lost one or more electrons polyatomic ion An ion consisting of more than one atom

Key Concepts The Structure of the Atom 2.1 charge = +1 ) and neutrons ( Atoms consist of a nucleus that contains protons relative ( relative charge = 0), and electrons (relative charge = −1 ), which are found in the region around the nucleus (2.1a). Protons and neutrons each have a relative mass of approximately1 u , whereas the relative mass of an https://ng.cengage.com/studycenter/index.html#/print/unitStudyGuides/MYJYOD921753099

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electron is 0 u (2.1a). An ion is an atom with an unequal number of protons and electrons. Anions have a negative charge because they contain more electrons than protons; cations carry a positive charge because they contain more protons than electrons (2.1a). Atoms are characterized by their atomic number (Z ), the number of protons in the nucleus, and their mass number (A ), the mass of the protons and neutrons in the nucleus. The mass number for an atom is essentially equal to the number of protons and neutrons in the nucleus (2.1b). The atomic symbol for an atom shows the element symbol X ( ), the atomic number, and the mass number (A Z X ) (2.1b). Isotopes are atoms that have the same atomic number but differ in their mass number (2.1c). The atomic weight of an element is the weighted average of the isotope masses of that element (2.1c).

Elements and the Periodic Table 2.2 The periodic table is an organizational chart used to arrange elements in horizontal periods and vertical groups (2.2a). Different regions and groups in the periodic table are given special names, such as main-group elements, transition elements, lanthanides, and actinides (2.2a). Most elements are metals, a smaller number are nonmetals, and the elements that have properties of both are metalloids (2.2a). Allotropes are forms of the same element that differ in their physical and chemical properties.

Covalent Compounds 2.3 Covalent compounds consist of atoms of different elements held together by covalent bonds (2.3a). Molecular covalent compounds consist of individual molecules, whereas network covalent compounds are made up of a three-dimensional network of covalently bonded atoms (2.3a). A molecular formula is the simplest way to represent a molecule and consists of element symbols and subscript numbers that indicate the number of atoms of each element in one molecule of the compound (2.3b). An empirical formula is the simplest whole-number ratio of elements in a compound (2.3b). Structural formulas and condensed structural formulas provide additional information about the atom connectivity in a molecule (2.3b). Wedge-and-dash models, ball-and-stick models, and space-filling models give information about the three-dimensional shape of a molecule (2.3c). Binary nonmetals, covalent compounds consisting of only two nonmetal elements, are usually named according to a set of simple rules (2.3d). Some covalent compounds such as inorganic acids, oxoacids, and hydrocarbons are named according to the composition of the compound or the relative number of atoms of each element in the compound formula (2.3d).

Ions and Ionic Compounds 2.4 Ionic compounds are made up of cations and anions and have physical and chemical properties that differ significantly from those of covalent compounds (2.4). https://ng.cengage.com/studycenter/index.html#/print/unitStudyGuides/MYJYOD921753099

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A monoatomic ion is a single atom that carries a positive or negative charge (2.4a). The charge on most main-group monoatomic ions can be predicted by the position of the element in the periodic table. The charge on a transition metal monoatomic ion can vary (2.4a). Polyatomic ions are groups of covalently bonded atoms that carry an overall charge (2.4b). Ions and ionic compounds are named according to a set of simple rules (2.4d). The formula of a compound can be used to determine whether it is a covalent or an ionic compound (2.4e).

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