How can we help?

You can also find more resources in our Help Center.

41 terms

Science ch 4

STUDY
PLAY
ion
an atom or a group of atoms that has an electric charge
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?
poly
many
polyatomic ions
ions that are made up of more than 1 atom
ionic bond
the attraction between two oppositely charged ions
ionic compound
a compound that consists of positive and negative ions
KI
Write the symbols for the ions that form when potassium and iodine react to form the ionic compound potassium iodide
Because potassium is 1+ and iodine is 1- making it electrically neutral
Why is potassium iodide electrically neutral?
chemical formula
a group of symbols that shows the ratio of elements in a compound
subscripts
numbers written below the line that tell how many atoms of a given type are in a compound.
superscripts
Used in footnotes or reference purposes.
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?
That there are 2 sodium atoms for every sulfur atom.
Explain what the formula Na2S means.
crystal
ions formed in an orderly, three-dimensional arrangement
covalent bond
a bond formed when atoms share one or more pairs of electrons
molecule
two or more atoms held together by covalent bonds
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?
double bond
a bond in which two atoms share two pairs of electrons
molecular compound
a compound that is composed of molecules
triple bond
a bond formed by sharing three pairs of electrons
valence electrons
electrons on the outermost energy level of an atom
electron dot diagram
a model of an atom in which each dot represents a valence electron
chemical bond
the force that holds two atoms together
octet rule
States that atoms lose, gain or share electrons in order to acquire a full set of eight valence electrons
electronegativity
a measure of the ability of an atom in a chemical compound to attract electrons
metallic bond
a bond formed by the attraction between positively charged metal ions and the electrons around them
alloy
a mixture of two or more metals
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?
solvent
substance in which a solute is dissolved to form a solution
solute
the substance that is dissolved
dissociate
to separate; to break association with
electrolysis
The process of decomposing a chemical compound by the passage of an electric current.
electronegativity trend
decreases from top to bottom in a group; increases from left to right in a period
malleability
the ability of a substance to be hammered or beaten into thin sheets
ductility
the ability of a substance to be drawn, pulled, or extruded through a small opening to produce a wire
luster
the way a mineral reflects light
conductivity
the ability of a material to allow either heat or electricity to flow through it
reactivity
the ability of a substance to combine chemically with another substance
insulator
a material that does not allow heat or electrons to move through it easily
semiconductor
an element that can conduct electricity under some conditions
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?