Ionic Bonds Answer Key

Student Exploration: Ionic Bonds Vocabulary: chemical family, electron affinity, ion, ionic bond, metal, nonmetal, octet rule, shell, valence electron Prior Knowledge Questions (Do these BEFORE using the Gizmo.) 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? Nate can give Clara a marker _________________________________________________________________________ 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? Maggie can give Fred and Florence each marker _________________________________________________________________________ Gizmo Warm-up Just like students sharing markers, atoms sometimes share or swap electrons. By doing this, atoms form bonds. The Ionic Bonds Gizmo allows you to explore how ionic bonds form. To begin, check that Sodium (Na) and Chlorine (Cl) are selected from the menus at right. Click Play ( ) to see electrons orbiting the nucleus of each atom. (Note: These atom models are simplified and not meant to be realistic.) 1. Each atom consists of a central nucleus and several shells that contain electrons. The outermost electrons are called valence electrons. (Inner electrons are not shown.) How many valence electrons does each atom have? Sodium: ______ 1 Chlorine: ______ 7 2. Click Pause ( ). Elements can be classified as metals and nonmetals. Metals do not hold on to their valence electrons very tightly, while nonmetals hold their electrons tightly. Electron affinity is a measure of how tightly the valence electrons are held. A. Try pulling an electron away from each atom. Based on this experiment, which atom Chlorine is a metal? ____________________ Which is a nonmetal? ____________________ Sodium B. Try moving an electron from the metal to the nonmetal. What happens? __________ ___________________________________________________________________ The nonmetal takes in the electron 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. (Electrons in the inner rings are not shown; you can assume these rings are full.) A. Observe the sodium and chlorine atoms. Assuming that the inner rings are full of electrons, how many electrons are there total in each atom? 11 Sodium: ____________________ Chlorine: ___________________ 17 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: ____________________ 11 Chlorine: ___________________ 17 2. 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: ____________________ 1 Chlorine: ___________________ 7 3. 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: _____ +1 Chlorine: _____ -1 Turn on Show charge to check. These charged atoms are called ions. B. Is each ion stable? Explain. Yes, ___________________________________________ now each atom has a full outer shell ___________________________________________________________________ Click Check in the lower right corner of the Gizmo to check. 4. Think and discuss: Why is there an attraction between the two ions in this chemical bond? _________________________________________________________________________ Neither of them had a full outer shell