Concept from Reading B.9, B.10, and B.11 (Tuesday Reading)

Main Concept

By Kelly Moran

The main concept from Tuesday's reading was to learn about periodic trends, ions, and ionic compounds. First I read about periodic trends which stated that elements were placed in columns (groups) in the periodic table based on their similar physical and chemical properties. The families all have similar physical and chemical properties while the rows (periods) have some similarities but not as much. Halogen elements when forming compounds are known as halide. In the reading there was a lab experiment shown that was testing whether halogen elements would react with halide compounds (basically testing the halogen elements as reactive or non-reactive). From already knowing they are reactive I would predict that the halogen elements would react to the halide compounds. I then read about ions and ionic compounds. Ions are electrically charged atoms. Ionic compounds are substances that are composed of both positive and negative ions (charges). Atoms gain or lose electrons to form negative and positive ions. For example, if you gain electrons (negative charge) the element will have a negative charge but if you lose electrons then you will have a positive charge. Typically the elements on the left of periodic table lose electrons and the elements on the right gain electrons. A crystal is sodium chloride that consists of equal numbers of positive sodium ions and negative chloride ions arranged in a 3-D network. A negatively charged ion is called an anion and a positively charged ion is called a cation. Chemists use the term formula unit when referring the simplest unit of an ionic compound. Polyatomic ions consists of many ions while monatomic ions consist of only one ion. A major difference between atoms of metals and nonmetals is that metal atoms lose electrons much more easily than do nonmetal atoms.