Ch. 5 Ionic Compounds Section 1 Simple Ions

Questions To Think About 1. What is the difference between an atom and an ion? 2. How can an atom become an ion?

For Review Define valence electrons. How many is an octet? What is an ion? What is a cation? An anion?

Chemical Reactivity How much an element reacts depends on the electron configuration. Noble gases are the least reactive elements. Compare the electron configuration of O (oxygen) to Ne (neon).

Chemical Reactivity [O] = 1s 2 2s 2 2p 4 Oxygen has only 6 valence electrons with only 4 in its p orbital. It can hold a total of 6. [Ne] = 1s 2 2s 2 2p 6 Neon has 8 valence electrons and its p orbital is completely filled.

Chemical Reactivity Noble gases are stable because their electron configurations have completely filled s & p orbitals in their outer shell. In most chemical reactions atoms tend to match the s & p electron configurations of the noble gases. This is known as the octet rule.

Valence Electrons Why does potassium lose one valence electron instead of gaining seven? Removing one requires far less energy than adding seven more.

Valence Electrons Ions – An atom or molecule that has gained or lost one or more electrons & has a positive or negative charge. Cation – K → K + + e - [K] = 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 [K + ] = 1s 2 2s 2 2p 6 3s 2 3p 6 (electron configuration just like argon)

Valence Electrons Anion – Cl + e - → Cl - [Cl] = 1s 2 2s 2 2p 6 3s 2 3p 5 [Cl - ] = 1s 2 2s 2 2p 6 3s 2 3p 6 (electron configuration just like argon)

Valence Electrons Practice Will calcium gain or lose electrons to form an ion? How many? Write the electron configuration for the calcium ion.

Valence Electrons How does an atom (parent atom) compare to the ion that it forms after it loses or gains an electron? Uses the same name Has the same number of protons & neutrons Has different chemical properties because of different #’s of electrons

Valence Electrons Remember an ion is different from a noble gas Ions have charge – so they form compounds Ions conduct electricity when dissolved in water Noble gases are unreactive and have none of these properties

Valence Electrons Stable ions that don’t have noble gas configurations Transition metals often form ions without complete octets With the exception of Re these are all cations Also can form stable ions with more than one charge

Valence Electrons

Homework Section Review 5.1 #’s 1, 3, 4, 5, 8,

PRACTICE PROBLEMS Please take a few minutes to do the following problems for practice.

10 11 ion octet anion cation 1. An atom or group of atoms that has a positive or negative charge because it has lost or gained electrons is a(n) ____________.

10 11 ion octet anion cation 2. The sodium ion has __________ protons, _________ neutrons, and ___________ electrons.

10 11 ion octet anion cation 3. In most chemical reactions, atoms tend to match the outer electron configuration of the noble gases. This is called the _________ rule.

Compete each statement below by writing the correct term or phrase. 4. An anion is an ion with a ____________ charge.

Compete each statement below by writing the correct term or phrase. 5. _________ electrons occupy the outermost energy level of an atom.

Compete each statement below by writing the correct term or phrase. 6. The chloride ion and the chlorine atom have ___________ electron configurations.

Compete each statement below by writing the correct term or phrase. 7. A cation is an ion with a ___________ charge.

Compete each statement below by writing the correct term or phrase. 8. Many stable ions have an electron configuration of a _____________.

Answer the following question. 9. How do the outer-shell electron configurations for ions of Group 1, Group 2, and Group 15, Group 16, and Group 17 elements compare with those of the noble gases?

9. How do the outer- shell electron configurati ons for ions of Group 1, Group 2, and Group 15, Group 16, and Group 17 elements compare with those of noble gases?