How is the reactivity of elements related to valence elecrons in atoms.
An atom is less likely to react if it has 8 valence electrons, but if it has less than 8, it will try to react with another atom so that it can have 8.
What does the periodic table tell you about atoms and the properties of elements?
it gives you information about the arrangement of electrons in atoms.
How many vaence electrons does each group of the periodic table have?
1:1
2:2
13:3
14:4
15:5
16:6
17:7
18:8
What is a valence electron?
an electron with the highest energy level that is held most loosely.
What is a chemical bond?
A chemical bond is the force of attraction that holds two atoms together as a result of the rearrangement of the electrons between them.
What are ions?
an atom or group of atoms that has an electric charge.
How do ions form bonds?
As a result of the attraction between positive and negative ions.
How are the formulas of ionic compounds written?
With the two chemical symbols of the elements written next to each other.
How are the names of ionic compounds written?
The name of the postitive ion followed by the name of the negative ion.
What are the properties of ionic compounds?
Hard brittle crystals with high melting points. they conduct electricity when dissolved in water.
What is a polyatomic ion?
A polyatomic ion is an ion made of more than one atom.
What holds covalently bonded atoms together?
The attraction of each atoms nucleus to the shared pair of electrons.
What are the properties of molecular compounds?
lower melting and boiling points, do not conduct electricity.
How does unequal sharing of electrons occur?
Atoms of some elements pull more strongly on shared electrons.
What is a polar bond?
a covalent bond where electrons are shared unequally.
What is a nonpolar bond?
A covalent bond where electrons are shared equally.
How do the properties of metals and alloys compare?
Alloys are generally stronger and less likely to react with air or water.