Chapter 4: Atoms and Elements Date:____________
Objectives:

Determine ion charge from numbers of protons and electrons.

Determine the number of protons and electrons in an ion.
Ions:

In chemical reactions, atoms often ______________ or _________________________________ to form charged particles called _____________. o Positive ions are called ___________________. o Negative ions are called __________________.

The ________________ of an ion is shown in the upper right corner of the symbol.

Ion charges are usually written with the magnitude of the charge first, followed by the sign of the charge. o Examples: ________________________
Ion Formation:

The ____________________ of an ion depends on how many electrons were _______________ or ________________ and is given by the following formula where _______ stands for proton and _______ stands for electron.

In reactions, lithium atoms lose _________ electron (e − ) to form Li + ions. o ____________________________

For the Li + ion with _______ protons and _______ electrons, the charge is o Ion charge = ______________ = _______

In reactions, fluorine atoms gain _________ electron (e − ) to form F − ions: o ____________________________

For the F − ion with ______ protons and _______ electrons, the charge is o Ion charge = ____________ = _______

Predicting Charge:

The _________________________ of the elements on the periodic table gives clues to the number of _________________________ electrons an atom has. o Valence electrons: the electrons found in the __________________________________ of an atom. There cannot be any more than _______ valence electrons in an atom.

In order to be _______________, elements want to have a __________ outer shell. o They want ______ electrons.

Atoms form ions in order to become more ________________.

The key to predicting the charge acquired by an element is its position in the periodic table relative to the ______________________________.

Main-group elements tend to form ions that have the same number of valence electrons as the nearest noble gas. o Alkali Metals (group 1) will form ________ ions o Alkaline Earth Metals (group 2) will form ________ ions o The Boron Group (group 3) will form ________ ions o Transition metals commonly form ________ or ________ ions, but can form greater than 3 + ions. o Halogens (group 17) will form ________ ions o Chalcogens (group 16) will form ________ ions o Pnictogens (group 15) will form ________ ions

Practice:
1.
Determine the charge of each ion. o Mg with 10 electrons o S with 18 electrons o Fe with 23 electrons
2.
Determine the number of protons and electrons in the Ca 2+ ion.
3.
Determine the number of protons and electrons in the S 2 ion.
4.
Based on their position in the periodic table, what ions do barium and iodine tend to form?