Science ch 4 Round 2
That there are 2 sodium atoms for every sulfur atom.
Explain what the formula Na2S means.
The attractions between the shared electrons and the protons in the nucleus of each atom hold the atoms together in a covalent bond
How are atoms held together in a covalent bond?
To write a formula for an ionic compound, write the symbol of the positive ion and then the symbol of the negative ion. Add the subscripts that are needed to balance the charges. For an ionic compound, the name of the positive ion comes first, followed by the name of the negative ion.
How are the formulas and names of ionic compounds written?
When a neutral atom loses a valence electron, it loses a negative charge. It becomes a positive ion. When a neutral atom gains an electron it gains a negative charge. It becomes a negative ion.
How do ions form?
octet rule
States that atoms lose, gain or share electrons in order to acquire a full set of eight valence electrons
electrolysis
The process of decomposing a chemical compound by the passage of an electric current.
superscripts
Used in footnotes or reference purposes.
Ionic bonds typically form between charged atoms of metals and nonmetals. Covalent bonds usually form between uncharged atoms of nonmetals.
What is the difference between ionic bonds and covalent bonds?
A metal crystal is composed of closely packed, positively charged metal ions. The valence electrons drift among the ions
What is the structure of a metal crystal?
Because potassium is 1+ and iodine is 1- making it electrically neutral
Why is potassium iodide electrically neutral?
KI
Write the symbols for the ions that form when potassium and iodine react to form the ionic compound potassium iodide
metallic bond
a bond formed by the attraction between positively charged metal ions and the electrons around them
covalent bond
a bond formed when atoms share one or more pairs of electrons
electronegativity
a measure of the ability of an atom in a chemical compound to attract electrons
electronegativity trend
decreases from top to bottom in a group; increases from left to right in a period
