Mr. Shepherd’s Physical Science Class
Name:___________________
Class: ___________________
Chapter 19: _______________________________________________
Section 2: _______________________________________________
 An atom that has LOST or GAINED electrons is called an ______________.
 An ____________________ is a charged particle, because it now has either
_____________ or _____________ ELECTRONS than protons.
 The POSITIVE and NEGATIVE charges are ________________________.
 BEFORE (INDIVIDUAL ELEMENTS): PROTONS = ELECTRONS
 NOW (GETTING READY TO FORM COMPOUNDS): PROTONS ≠
ELECTRONS
 Some of the most common compounds are made by the _______________
and _____________________ of just 1 ____________________________.
(Group 1 element + Group 17 element) Ex. NaCl
 Examples…Sodium chloride (table salt); sodium fluoride (anticavity
ingredient in toothpaste); and potassium iodide (ingredient in iodized salt)
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What happens when Sodium and Fluorine come together?
Na
 LOSES AN ELECTRON Na+
(1 LESS ELECTRON = POSITIVE CHARGE)
The 1+ charge is shown as a superscript written _____________________
the element’s symbol, Na+, to indicate its charge.
F
GAINS AN ELECTRON
F(1 MORE ELECTRON = NEGATIVE CHARGE)
RESULT: The compound has a neutral charge, because positive and
negative charges of the ions cancel each other. Ex. NaF (Another Ex. Na+
and Cl
NaCl
)
 An ______________________ is a force of attraction between the opposite
charges of the ions in an ionic compound. (Metal + Nonmetal)
 Ionic bond with more than 1 electron involved…
MgCl2
MagnesiumGroup 2 and ChlorineGroup 17
 At the same time, 2 chlorine atoms GAIN 1 electron each and become
NEGATIVE charged ions, Cl-.
 A MAGNESIUM atom has 2 electrons to LEND, but a single CHLORINE atom
needs to BORROW only 1 electron.
 Therefore, it takes 2 chlorine atoms to take the 2 electrons from the 1
magnesium ion.
 Magnesium LOSES 2 electrons = Mg2+
 2 Chlorine atoms GAIN 2 electrons = Cl(Each Cl atom GAINS 1 electron)
Cl-
 The ___________________ CHARGE of the 1 magnesium ion is exactly
________________ to the ______________ CHARGE of the 2 chloride ions.
 ***Therefore, the compound is __________________________.
 ***_____________________ usually are formed by bonding between
__________________ and _________________ (losing/gaining electrons).
(Examples: NaCl and MgCl2)
 Some atoms of ________________ are unlikely to LOSE or GAIN electrons.
 For example, the elements in GROUP 14 have 4 electrons in their outer
energy level. They would have to lose or gain 4 electrons in order to have a
stable outer energy level.
 The loss of this many electrons takes a great deal of energy. Each time an
electron is removed, the nucleus holds the remaining electrons even more
tightly.
 The attraction that forms between atoms when they SHARE electrons is
known as a _______________________.
 A neutral particle that forms as a result of electron sharing is called a
__________________________.
 O = 6 electrons
 H = 1 electron
 H = 1 electron
 2 SINGLE COVALENT BONDS
Covalent Bonds
 Electrons are not always shared equally between atoms in a covalent bond.
 The strength of the attraction of each atom ot its electrons is related to…
 SIZE of the atom
 CHARGE of the nucleus
 TOTAL NUMBER OF ELECTRONS the atom contains.
 A ____________________________________ is one that has a slightly
positive end and a slightly negative end, although the overall charge is
NEUTRAL.
 A ____________________________________ is one in which electrons are
shared equally in bonds.