INTRODUCTION TO IONS

Transcription

1 Name: INTRODUCTION TO IONS Block: Vocabulary: chemical family, electron affinity, ion, ionic bond, metal, nonmetal, octet rule, shell, valence electron Review 1. What are the 3 subatomic particles of an atom? 2. What do we call the outermost shell of an atom? What do we call the subatomic particles in this shell? 3. Which family has the least amount of valence electrons? Which family has the most? (How many do they each have?) 4. Draw a Bohr Diagram for: Lithium Fluorine a. What is the ion charge for LITHIUM? b. What is the ion charge for FLUORINE? c. Why do you think Lithium is positive and Fluorine is negative?

2 Let s look at a couple of general examples first 1. Nate and Clara are drawing pictures with markers. There are 8 markers in a set. Nate has 9 markers and Clara has 7. What can Nate and Clara do so that each of them has a full set? 2. Maggie is sitting at a table with Fred and Florence. Maggie has 10 markers, but Fred and Florence each have only 7 markers. How can they share markers so each has 8? What do markers and sharing have to do with Chemistry?? All atoms want to have a full outer orbital to be stable. This means that most atoms will need to have 8 electrons in their outermost shell. We call this a. An atom can gain or lose electrons to obtain a stable octet. Atoms that have gained or lost electrons are called and therefore carries a. How do atoms become ions? a. Atoms that electrons have a charge and are called b. Atoms that electrons have a charge and are called c. The Noble Gases have full outer orbits and therefore do not gain/lose electrons *NOTE: Protons are NOT exchanged; an element will ALWAYS have the same number of protons. Examples: a. Sodium loses 1 electron to become a positive (+1) ion. b. Magnesium loses 2 electrons to become a positive (+2) ion. c. Chlorine gains 1 electron to become a negative (-1) ion.

3 Group # electrons in valence shell Gain/Loss of Electrons Charge 1 1 Lose (He has 2) Do not gain/lose No charge Lithium Fluorine

4 Beryllium Magnesium Aluminum Potassium

5 Carbon Oxygen Phosphorus Chlorine Conclusion: Non-metals gain electrons to become ions and always have a negative ion charge. Metals lose electrons to become ions and always have a positive ion charge.

6 Vocabulary Chemical family a vertical column in the periodic table of elements. o Elements in the same family have the same number of valence electrons and have similar chemical properties. Electron affinity the tendency of an atom to attract electrons. o Electron affinity is a measure of the energy required to remove an electron from the atom. This value is also called ionization energy. o Nonmetals are characterized by a high electron affinity, while metals are characterized by a low electron affinity. Ion an electrically charged atom that has gained or lost one or more electrons. o An atom with more protons than electrons is a positively charged ion, or cation. o An atom with more electrons than protons is a negatively charged ion, or anion. o In an element symbol, the electric charge is shown at the upper right. Ionic bond a bond formed by the attraction between two oppositely charged ions. o Positively charged ions attract negatively charged ions and vice versa. o Positively charged ions repel positively charged ions. o Negatively charged ions repel negatively charged ions. Metal an element that is malleable and usually conducts heat and electricity well. o Metal atoms tend to lose electrons when forming chemical bonds. Nonmetal an element that is generally a poor conductor of heat and electricity. o Nonmetal atoms tend to gain or share electrons when forming chemical bonds. o Most nonmetals are gases at room temperature. Octet rule a rule of thumb that states that atoms are most stable when surrounded by eight valence electrons. o Metals lose valence electrons to obtain a stable configuration. o Nonmetals gain or share electrons to obtain a stable configuration. o Elements with five or fewer electrons are exceptions to the octet rule because they become stable when they have two valence electrons. Shell a particular region where electrons can orbit the nucleus of an atom. Valence electron an electron in the outermost shell of an atom.