Atoms have NO overall charge

1. Atoms have NO overall charge • ATOMS DO NOT HAVE A CHARGE BECAUSE THEY HAVE AN EQUAL NUMBER OF PROTONS AND ELECTRONS WHO CHARGES EXACTLY CANCEL! • A CHLORINE ATOM HAS 17 PROTONS, WHICH MEANS IT HAS 17 ELECTRONS ALSO… • NEUTRONS HAVE NO CHARGE. • BUT…if an electron is removed from an element then things change…

2. Every Atom has one or more valence electrons Valence Electrons: an electron in the outermost energy level of an atom. There can only be 2 electrons in the first energy level. E 7 protons Nitrogen (N) 7 electrons The second energy level can hold 8 electrons & every level after that. E E 2 e-’s E E Nitrogen’s electrons only fill up five of the second shell. So this means there are 5 valence electrons for Nitrogen (the same as the group they are found in on the periodic table – 5A) E E 8 e-’s 8 e-’s

3. An octet is a set of 8. An energy level can hold up to 8 electrons in its outer most energy level. Atoms of metallic elements tend to lose their valence electrons leaving a complete octet in the next lowest energy level. Atoms of some nonmetallic elements tend to gain electrons or share electrons with another nonmetallic element to achieve a complete octet.

4. Ionic Bonds • Ionic Bonds form when elements do not have complete sets of valence electrons. This usually occurs between a metal cation and a nonmetal anion. • Some elements achieve stable electron configurations through the transfer of electrons between atoms. • Transfer of electrons takes place when one electron is donated or accepted from one atom to another.

5. Ionic Bonds Cont. • Formation of Ionic Bonds= When an atom gains or loses an electron it becomes an ion • An ion is a charged particle which can bond with another charged particle • A CATION is a positively charged atom, such as Na+ or H+ or Be2+ , etc. • A ANION is a negatively charged atom, such as I-, Cl-, S2-, N3-, etc. • Sharers, such as Carbon usually bond covalently and share electrons.

6. Let's Practice • Would Lithium (Li) be a cation or anion? • Would Hydrogen (H) be a cation or anion? • Would Nitrogen (N) be a cation or anion? • Would Florine (F) be a cation or anion? • Boron? • Aluminum? • Calcium? Cation + 1 Cation +1 Anion 3- Anion 1- Cation 3+ Cation 3+ Cation 2+

7. Ionization Energy & Ionic Compounds • An electron can move to a higher energy level when an atom absorbs energy. • The amount of energy used to remove and electron is called IONIZATION ENERGY • The Trends are as follows on the periodic table. Generally increases Generally decreases • Ionization: the process of adding electrons to or removing electrons from an atom or a group of atoms.

8. - Ionic Bonds Properties of Ionic Compounds • In general, ionic compounds are hard, brittle crystals that have high melting points. When dissolved in water or melted, they conduct electricity.

9. - Ionic Bonds Ions and Ionic Bonds • You and a friend walk past a market that sells apples for 40 cents each and pears for 50 cents each. You have 45 cents and want an apple. Your friend also has 45 cents but wants a pear.

10. - Ionic Bonds Ions and Ionic Bonds • When an atom loses an electron, it loses a negative charge and become a positive ion. When an atom gains an electron, it gains a negative charge and becomes a negative ion.

11. 5.1 The Bohr Model • Bohr proposed that an electron is found only in specific circular paths, or orbits, around the nucleus. • What was the new proposal in the Bohr model of the atom? • Each possible electron orbit in Bohr’s model has a fixed energy. • The fixed energies an electron can have are called energy levels. • A quantum of energy is the amount of energy required to move an electron from one energy level to another energy level.

12. ENERGY LEVEL: any of the possible energies an electron may have in an atom. Like the building shown here… electrons cannot be between floors. 4th Energy Level 8 e- 8 e- 3rd Energy Level 8 e- 8 e- 2nd Energy Level 2 e- 2 e- 1st Energy Level Nucleus

13. Sodium (Na) If the first energy level only has two electrons then electrons are located in the next energy level. For example, Sodium p = 11 e= 11 n= 12 After the first two electrons take up the first energy level, 9 more electrons are located in different energy levels. Only 8 electrons can fill up the second energy level. This is called the octet rule. So the last electron is located in the last level, all by itself! This is what gives sodium a (+1) charge when it becomes ionized.

14. Let’s Practice!

16. Let’s Practice! # of Valence Electrons: ______ Charge as an Ion: _________ # of Valence Electrons: ______ Charge as an Ion: _________ # of Valence Electrons: ______ Charge as an Ion: _________ # of Valence Electrons: ______ Charge as an Ion: _________ # of Valence Electrons: ______ Charge as an Ion: _________ # of Valence Electrons: ______ Charge as an Ion: _________

17. Ga K Mg Ni

20. Stable Electron Configuration • When the outermost energy level of an atom is filled with electrons, the atom is stable and not likely to react. • An electron dot diagram is a model of an atom in which each dot represents a valence electrons. • Atoms can bond with one another by switching, sharing, or exchanging electrons with one another.

21. - Atoms, Bonding, and the Periodic Table Valence Electrons and Bonding • The number of valence electrons in an atom of an element determines many properties of that element, including the ways in which the atom can bond with other atoms.

22. - Atoms, Bonding, and the Periodic Table The Periodic Table • As the number of protons (atomic number) increases, the number of electrons also increases. As a result, the properties of the elements change in a regular way across a period.

23. - Ionic Bonds Ions and Ionic Bonds • Ionic bonds form as a result of the attraction between positive and negative ions.