Electron Dot Diagrams and Lewis Dot Structures Ms. Dice

Valence electrons How can we find the number of valence electrons for an element? Draw the electron configuration. OR Look at the periodic table! The group number represents the number of valence electrons the elements in that group will have.

Bonding basics How do the elements in salt combine to create salt? Two or more elements can combine to form substances called compounds. What two elements make up salt? Na and Cl Sodium and Chloride

The elements number of valence electrons Electron Dot Diagram Before we can understand how sodium and chloride come together to create salt, we need to be able to represent elements in a simplified way. The Electron Dot Diagram is a simplified model that represents an elements valence electrons. Below are the things that you need to be able to find on the periodic table before you can draw an Electron Dot Diagram. An elements symbol The elements number of valence electrons

Chloride Cl 7 valence electrons Electron Dot Diagram Step 1: Find the element on the periodic table. Step 2: Recognize and write down the symbol of the element. Step 3: How many valence electrons does it have? Step 4: Moving clockwise, add valence electrons around the element symbol until all the valence electrons are represented. Chloride Cl 7 valence electrons

Practice Problems Now that we have gone over an example, lets practice by completing part 1 on the worksheet handed out.

Ionic Bonding An atoms that gains or loses one or more electrons is called an ion. An atoms wants to have 8 valence electrons. When elements combine to make a compound, they must gain or lose electrons. When an atom loses an electron, it will have a positive charge. We call this an cation. When an atom gains an electron, it will have a negative charge. We call this an anion. What charge would a neutral atom have?

Ionic Bonding An ion is a particle that has a positive or negative charge. Ions form when atoms or molecules gain or lose an electron. An ionic bond is the attraction between ions with opposite charges. A compound that forms from an ionic bond is called an ionic compound (like salt NaCl). Example: Salt= Sodium Chloride Na Cl Draw the Lewis Dot Structure for Na. Draw the Lewis Dot Structure for Cl. Draw an arrow showing which electrons will be lost/gained and where. Which ion is the cation? Which ion is the anion?

Covalent Bonding Some atoms do not transfer electrons easily. These atoms may bond by sharing electrons. When electrons are shared, they move around the nucleus of all the atoms instead of just one of them. A bond that forms when atoms share electrons is called a covalent bond. A covalent bond forms between two nonmetals.

Polar Bonding In a polar covalent bond, the atoms in the bond do not share their electrons equally. The electrons spend most of their time around one of the atoms. In water, the oxygen atoms attract electrons more than the hydrogen atoms do. This means the electrons are going to spend more time around the oxygen atom, giving it a negative charge.