7. Sadbaks 9. Cesium, Strontium, Arsenic, Phosphorus, Fluorine, Helium 10. It means it is unstable will react with element or a group that has negative electron affinity as it ha deficiency of electrons. 11. The halogens in Group 7A (17) all have large negative electron affinities, since they are only one electron away from having a noble gas configuration, they easily accept another electron to generate stable halide anions. Chemical Bonding Atoms have the ability to do two things in order to become isoelectronic with Noble Gas
Electrons can be transferred from one atom to another forming ions. Positive ions (cations) are formed when metals lose electrons. Negative ions (anions) are formed when non-metals gain electrons. The electrostatic attraction between the oppositely charged ions forms an ionic bond. Electron pairs can also be shared between two atoms. The mutual attraction of the electrons by each atom is called a covalent bond . Lewis (Electron Dot) Diagrams are used to show ionic bonding. 2.1 The Formation of Ionic and Covalent Bonds pg. 59 #1-6, pg. 63 #1-4 1. The octet rule: When bonds form between atoms, the atoms gain, lose, or share electrons in such a way that they create a filled outer shell containing eight electrons. It can be applied to the way H 2 O shares electrons. 2. If there is 2 bromine atoms and one calcium atom, the calcium atom will give up 2 electrons, one for each bromine atom. 3. Determine the total number of valence electrons that each of the atoms in the compound should have and add them together, count the number of electrons shown in the Lewis structure. If the numbers are equal, it’s a molecular compound. If not, it’s a polyatomic. 4.
5. Double bonds are covalent bonds that result from atoms sharing two pairs of electrons. Triple bonds are covalent bonds that result from atoms sharing three pairs of electrons. 6. A situation in which two atoms that are covalently bonded together can be part of an ionic compound is if a polyatomic ion formed into an ionic compound with a metal. 1. The property that they have a full valence shell and are stable led to the octet rule. The octet rule states that atoms form ionic and covalent bonds to become stable, just like the noble gases. 2. Metal ions tend to lose electrons because they usually have 1, 2 or 3 valence electrons. Non-metals tend to gain electrons because they have 5, 6 or 7 valence electrons. 3. & 4. pg. 63 #7,8,10,11,12,14,15,16 7. 8. Polyatomic ion; NO 3 - because there are not enough electrons. 10. a) C2.5 – F4.0 = 1.5 polar covalent b) O3.5 – N3.0 = 0.5 polar covalent c) Cl3.0 – Cl3.0 = 0 true covalent d) Cu1.9 – O3.5 = 1.6 polar covalent e) Si1.8 – H2.1 = 0.3 slightly f) Na0.9 – F4.0 = 3.1 Ionic g) Fe1.8 – O3.5 = 1.7 polar covalent h) Mg 1.2 – O3.5 = 2.3 Ionic 11.
12. O/N, C/S, Na/Cl, H/Cl 14. It’s called a dipole (2 poles) meaning the cross is a plus (positive) and the arrow refers to negative.