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Bonding and Ions
Transcript of Bonding and Ions
Called valance electrons
What are ions? Which elements are lenders? Which elements are borrowers? How to get a happy atom? Covalent Bonding A bond between 2 non-metals Where electrons are shared equally. They share electrons to become "happy". Sad atoms do not have full valence shells Sharing electrons allows them to have a full valence layer Ionic Bonding A bond between a metal and a non-metal. This is an unequal sharing with borrowers and lenders. Full valence layers have 8 electrons. This is called the octect rule: Oct- the prefix for 8 like octagon, or octapus How likely 2 elements will bond depends on their electrons. Many elements are unstable when not bonded. Atoms will give or take electrons to get 8 electrons in the valence shell. Remember the Alkali Metals in water? They react (create a bond) with water instantly, because they are unhappy. When an atom shares electrons,
it either lends or borrows. Atoms that have a charge due to bonding. Lending electrons: e This atom will give away this electron. 11p+ 11e- 11p+ This atom has 11+ and 11-, so it is neutral. +11-11=0 IT BONDS The electron is gone!
It has been given away. 10e- There are 10 electrons in the outer layer now. The outer shell is empty, so it disappears It is now happy. BUT! This atom has +11p and -10e, it has a +1 charge. It became an ion. +11-10=1 Sodium Sodium ion Nothing else changed! It is still Na, because the protons have not changed. Some elements do not bond at all. Which chemical family already has a full octect? Nobel gases do not bond.
They are chemically inert because they are happy. Giving atoms become positive ions. Borrowing electrons: Fluorine atom 9p+ 9p+ There is a space for an electron
The valence is not full. e This atom took an electron, now it has a full valence shell IT BONDS 9e- 10e- Again, +9 and -9 balance, the atom is neutral. +9-9 = 0 Fluorine ion It has +9 and -10, it has become a negative ion. +9-10 = -1 There are more electrons than protons.
Taking atoms became negative ions. Protons have not changed, so it is still F. There are now 10 valence electrons The atom is happy. BUT! Ions are created in this bonding example: Valence electrons we will ignore the trasitional metals for now Notice how the periodic table is organized The groups share valence electrons Rows are the number of shells. You can tell a lot about an element by just looking at the table. Groups with 4 or less valence electrons give or lend: Alkali metals
Alakiine earth metals
"Carbon" group It is easier for them to give up electrons. Atoms may want to be happy, but they do not want too many extra negative electrons. So they lend instead. Groups with 4-7 valence electrons take or borrow: Carbon group
Halogens The carbon group is in the middle, so it sometimes is a borrower, sometimes a lender, or both. It is easier for these elements to take or borrow electrons. They want to be happy, but they do not want to give electrons. This would make them too positive So they take electrons. Magnesium Oxygen 12p+ 8p+ 12e- 8e- There are 2 "extra" electrons Oxygen has 2 spaces in it's valence Magnesium 8p+ 12p+ 10e- 10e- Oxygen 2 e- move from Mg to O Total:
The compound is neutral! Mg is now smaller, because the p+ have more pull on the e-. O is larger, because more e- pull away from the p+ Covalent bonding, atoms are both lenders and borrowers. With electrons going back and forth between the 2.
Carbon +2 ion -2 ion Nonmetals: Phosphorus
Selenium Remember the Noble gases do not bond Example: Oxide This is the oxygen we breathe in. Oxygen 8p+ Oxygen 8p+ Both O atoms will share these electrons. Oxygen Oxygen 8p+ 8p+ The 4 e- are shared between the O atoms
So they each in turn have a full valence. They are not ions because the charge is always changing. The electron clouds overlap their valence layers Each O atom has 2 empty slots. outermost electrons