Question

activity a: ions
get the gizmo ready:

• click reset.
• check that sodium and chlorine are still selected.

introduction: some of the particles that make up atoms have an electrical charge. electrons are negatively charged, while protons are positively charged. particles with opposite charges (+ and -) attract, while particles with the same charge (+ and + or - and -) repel.
question: what happens when atoms gain or lose electrons?

1. count: electrons move around the nucleus of atoms in specific shells, shown by the rings around the atoms in the gizmo. the first ring holds two electrons, and the second holds eight. (if you like, you can hide the inner electrons by selecting hide inner electrons.)

a. observe the sodium and chlorine atoms. how many electrons are there total in each atom?
sodium: ____________ chlorine: ____________
b. each atom is neutrally charged, which means that each atom has the same number of protons and electrons. based on this, how many protons are in each atom?
sodium: ____________ chlorine: ____________

1. observe: most atoms are stable with a configuration of eight valence electrons. this is known as the octet rule. how many valence electrons does each atom have?

sodium: ____________ chlorine: ____________

1. form a bond: each electron has a charge of 1−, and each proton has a charge of 1+. you can calculate the charge of an atom by subtracting the number of electrons from the number of protons. move an electron from the sodium to the chlorine atom.

a. what are the charges of each atom now? sodium: ____ chlorine: ____
turn on show charge to check. these charged atoms are called ions.
b. is each ion stable? explain. ______________
click check in the lower right corner of the gizmo to check.

1. think and discuss: why is there an attraction between the two ions in this chemical bond?

Explanation:

Step1: Recall atomic number for electron - proton count

The atomic number of sodium (Na) is 11 and for chlorine (Cl) is 17. In a neutral atom, the number of electrons equals the number of protons which equals the atomic number.

Step2: Determine valence electrons

Sodium has an electron - configuration of 2, 8, 1, so it has 1 valence electron. Chlorine has an electron - configuration of 2, 8, 7, so it has 7 valence electrons.

Step3: Calculate charges after electron transfer

When an electron moves from sodium to chlorine: Sodium loses 1 electron, so its charge is \(+ 1\) (11 protons and 10 electrons). Chlorine gains 1 electron, so its charge is \(-1\) (17 protons and 18 electrons).

Step4: Analyze ion stability

Sodium ion is stable because it has a full outer - shell (the second shell with 8 electrons). Chlorine ion is stable because it has a full outer - shell (the third shell with 8 electrons).

Step5: Explain ion attraction

Oppositely charged ions attract each other. Sodium ion is positively charged and chlorine ion is negatively charged, so they are attracted to form an ionic bond.

Answer:

1.
A. Sodium: 11, Chlorine: 17
B. Sodium: 11, Chlorine: 17

1. Sodium: 1, Chlorine: 7

3.
A. Sodium: \(+1\), Chlorine: \(-1\)
B. Both ions are stable. Sodium ion has a full outer - shell (8 electrons in the second shell) and chlorine ion has a full outer - shell (8 electrons in the third shell).

1. There is an attraction between the two ions because sodium ion has a positive charge and chlorine ion has a negative charge, and opposite charges attract each other to form an ionic bond.