Elements & the Periodic Table

1. Elements & the Periodic Table All in the family

2. Periodic Law • Physical and Chemical properties of the elements recur in a repeating pattern when ordered by increasing atomic number Z • Elements arranged by increasing Z in horizontal rows called Periods and columns called Groups • Elements in the same group have similar change and physical properties • Elements in the same group have the same number of valence electrons (electrons in the outermost energy level of the atom) • It is the number of valence electrons that is responsible for chemical reactivity

3. Identifying elements in the same group • Because members of the same group have similar chemical properties we often can identify which elements belong to the same group (family) by studying their chemical reactions • We will study 3 groups • Alkali metals • Alkaline Earth metals • Halogens • Like brothers and sisters elements within a family still have individual characteristics that make them unique • We will identify ”family traits”, and what makes elements unique

4. Being Safe – using ions not elements • Alkali metals, alkaline earth metals, and halogens are all really dangerous as elements • Alkali metals for example can explode in water/air • We will use aqueous ions, (ions dissolved in water), of the metals and halogens. • We will use say sodium ion solutions, since the ions from the same group also behave according to “family traits” like the elements do • According to periodic law, the ions of the same group behave similarly since they too have the same number of valence electrons and the same charge

5. Part A: Flame Tests for Metal Ions • In Part A, you will perform a flame test of six solutions each containing an alkali, or alkaline earth metal ion • A flame test is where you take a metal loop dip it into the solution of interest and place the wet metal loop into a blue Bunsen flame. • As the metal ions heat up the electrons get excited to higher energy states, and as they then cool down they release the energy as light with a specific color, unique to that ion. • Each metal ion produces a different color, helping you to distinguish each metal ion from the others

6. Part B: Chemical reactions of the metal ions • In Part B, you will examine the behavior of the six metal ions in 3 different reactions • With Barium for example you will study 3 reactions • With ammonium carbonate • With ammonium hydrogen carbonate • With ammonium sulfate • You may observe a solid forming (precipitation) or no reaction at all. • If a solid forms we say a chemical reaction has occurred. • When a solid forms the solution goes cloudy, because the grains of solid are small and suspended in solution • You will use the results of Part B to classify the six metal ions into two groups (families) which share similar chemical properties

7. Part C: Chemical Properties of the halogen ions • In Part C you will examine the distinct behavior of the 3 halogen ions • You will see what happens when then react with • Bleach (sodium hypochlorite) • A similar reaction happens but the color at the end is different for each halogen • Each color is characteristic of that particular halogen ion, so you can distinguish one halogen from another

8. Part D: Identify a Mystery Solution • In part D you will apply the testing procedures and data you gathered in parts A-C to identify the metal ion and the halogen present