Lessons 17-19

Lesson 17

On Friday we did a flame test, which is a test done to see if there is a presence of metal atoms. We dipped rods in different chemical compounds and stuck that in a bunsen burner and made notes on the colors and patterns we saw. For the color to change we needed light energy. That is created when an excited electron moves to the next shell of an atom. When the electro moves back to it's original shell light energy is produced.

Practice Problems
1. Groups in the periodic table have similiar properties which means they turn certain colors. When performing a flame test if you see a color you can look on the periodic table and make connections to the elements that produce a similiar color to find out what it is.
4. I think it will be a yellow-orange because other compounds that contain sodiu are that color.


Lesson 18

In lesson 18 we learned more about electrons. The period number in the table is equal to the number of shells required to hold that elements electrons. And the group number is equal to the number of valence electrons that element has. We also learned that core electrons are all the electrons except the valence electrons.

Practice Problems
2. An elements group tells you how many valence electrons it has. If the element is neutral then it will have the same number of electrons as protons, allowing you to arange the electrons in shells of 2, 8, 8, or 18 if the element is after the transition metals.
3. They all have 2 valence electrons.


Lesson 19

In this lesson we learned about ions. An ion is an atom with a positive or negative charge because of lost or gained electrons. A cation is an ion with a positive charge and an ion with a negative charge is called an anion. Superscript denotes the charge of an atom. We also learned that metal atoms transfer electrons to nonmetals when they form compounds.


Practice Problems

1. An anion is an ion with a negative charge and a cation is an ion with a positive charge.
2. Noble gases have a full valence shell and are unreactive. The other elements are "jealous" because they too want that full shell.