Chap 3. Molecules, compounds, chemical equations Flashcards
(50 cards)
Chemical bonds
compounds are composed of atoms held together by chemical bonds. Chemical bonds are the result of the interactions between the charged particales (electrons and protons) that compose atoms.
What kind of Chemical bonds are there?
Ionic bonds and covalent bonds
Ionic bonds
metals and nonmetals
transfer of electrons from one atom to another.
Metals have a tendency to lose electrons and that nonmetals have a tendency to gain them. therefore, when a metal interacts with a nonmetal, it can transfer one of more of its electrons to the nonmetal.
Covalent Bonds
2 or more nonmetals
sharing of electrons between 2 atoms
What attracts atoms to each other in Ionic bonds?
the oppositely chared ions are attracted to one another by electrostatic forces, it is not because they share electrons (those are covalent bonds)
In chemical formulas what is listed first?
usually more metallic substances (more positively charged) then the less metallic substance (or more negatively charged)
what is the difference between an empirical formula and a molecular formula?
empirical formula gives the relative number of atoms of each element in a compound ex (HO, hydrogen peroxide)
MOLECULAR formula gives the actual number of atoms of each element in a molecule of a compound. hydrogen peroxide (H2O2).
what is the name of the type of formula that gives the most information and is drawn out to show bonds etc…
structural formula
Define atomic elements as opposed to molecular elements
Atomic elements, elements that exist in nature with single atoms as their basic units. most elemenst fall into this category (Al, Fe He)
MOLECULAR elements, they do not normally exist in nature with single atoms as their basic units. Instead, these elements exist as MOLECULES, 2 or more atoms of the element bonded together. (N2, Cl2, H2 DIATOMIC)
only a few MOLECULAR ELEMENTS fall into the POLYATOMIC MOLECULES category (P4, phosphorous)
how many elements exist as diatomic molecules?
7, looks like the number on periodic table, H, N, O, F, Cl, Br, I
how many elements exist as polyatomic molecules?
3, covered by the 7 that are in table
(P, S, Se). to the left of the seven diatomic elements
Molecular compounds
usually composed of 2 or more covalently bonded nonmetals. the basic units of molecular compounds are molecules composed of the consituent atoms. For example, water is composed of H2O molecules, dry is composed of CO2 molecules.
Ionic compounds
composed of catoins (usually one type of metal) and anions (usually one or more nonmetals) bound together by ionic bonds.The basic unit of an ionic compound is the formula unit, the smallest electrically neutral collection of ions. Formula units are different from molecules in that they do not exist as discrete entities, but rather as part of a larger lattice. for example, the ionic compound table salt, with the formula unit NaCl, is composed of Na+ and Cl- ions in a one to one ration. In table salt, ,Na+ and cl- ions exist in a 3 dimensional array. however, because ionic bonds are not direction, no one Na+ ions pairs with a specific Cl- ion. Rather any one Na+ is surrounded by Cl- anions and vice versa.
polyatomic ion
many common ionic compounds conatin ions that are themselves, composed a group of covalently bonded atoms with an overall charge. for exampole, the active ingredient in household bleach is sodium hypochlorite, which acts to chemically alter color causing molecules in clothes, hypochlorite is a POLYATOMIC ION. an ion composed of 2 or more atoms0 with the formula ClO-. (note that the charge on the hypochlorite ion is a property of the whole ion, not just the oxygen atom)
Summarize Ionic compound formulas
ionic compounds always contain positive and negative ions
in a chemical formula, the sum of the charges of the positive ions (cations) must always equal the sum of the charges of the negative ions (anions)
the fomula reflects the smallest whole-number ration of ions.
Naming ionic compounds
some ions always have the same charge no matter what kind of compound they are in.
however there are some that change depending on the type of compound they are in.
what are the elements that do not change their charge from one compound to another in Ionic compounds?
Basically all the elements in the first 2 columns (families, groups) and a few others,
Sc (3+) Al(3+) Zn (2+) Ag (silver +)
binary compounds
contain only 2 different elements.
how do you name binary ionic compounds that contain a metal that only forms one type of cation. ?
KCL, potassium chloride
just add ide, no need to put the (II) or (III) after the first because these are ones that never change.
C2H3O2
Acetate-
CO3
Carbonate 2-
HCO3
Hydrogen carbonate or bicarbonate -
OH
hydroxide
NO2
Nitrite -
