Ch 6 Flashcards
Chemical bond
attractive force holding two or more atoms together
Ionic bond
- results from the attraction of negative and positive ions
- Usually, a metal forms the positive ion and a nonmetal forms the negative ion
Covalent bond
- results from sharing electrons between the atoms
- Usually found between nonmetals
Atoms acquire octets
- By forming compounds.
- To become more stable.
- By losing, gaining, or sharing valence electrons.
Metals form
- Octets by losing all of their valence electrons.
- Positive ions with the electron configuration of the nearest noble gas.
- Positive ions called cations
In ionic compounds, nonmetals
- Achieve an octet -arrangement.
- Gain electrons.
- Form negatively charged ions with 3-, 2-, or 1- charges.
The charge of a positive ion is equal to
its Group number.
The charge of a negative ion is obtained by
subtracting 8 (or 18) from its Group number
Ionic compounds
- Consist of positive and negative ions.
- Have ionic bonds between positively and negatively charged ions.
- Have high melting and boiling points.
- Are solid at room temperature
An ionic formula
- Consists of positively and negatively charged ions.
- Is neutral.
- Has charge balance. total positive charge = total negative charge
- Uses subscripts to indicate the number of ions needed to give charge balance.
In an ionic formula
- The symbol of the metal is written first followed by the symbol of the nonmetal.
- The charges of the ions in the compound are not shown.
The formulas of ionic compounds are determined from the
charges on the ions
Naming of Ionic Compounds : First word of name
Name of metal in full
Naming of Ionic Compounds : Second word of name
Name of anion stem (second element in formula) with “-ide” ending
Transition metals
With two different ions use a Roman numeral after the name of the metal to indicate ionic charge.
A polyatomic ion is
a group of atoms with an overall ionic charge.
The names of common polyatomic anions
- Most common ends in ate.
- With one oxygen less end in ite
- With hydrogen attached use prefix hydrogen (or bi).
The formula of an ionic compound
- Containing a polyatomic ion must have a charge balance that equals zero(0).
- With two or more polyatomic ions encloses the polyatomic ions in parentheses.
Diatomic Elements
These elements share electrons to form diatomic, covalent molecules.
Electron-dot formulas show
- The order of bonded atoms in a covalent compound.
- The bonding pairs of electrons between atoms.
- The unshared (lone) valence electrons.
- A central atom with an octet
Prefixes are used
- In the names of covalent compounds.
- Because two nonmetals can form two or more different compounds.
Naming Covalent Compounds
- Name the first nonmetal as the element
- End the name of the second metal with -ide
- Use prefixes to show the number of atoms (Subscripts).
Mono is usually omitted
Guide to Writing Formulas
STEP 1 Write the symbols in the order of the elements in the name.
STEP 2 Write any prefixes as subscripts.
