Isotopes and Elements Practice Problems

This lesson will define and explain elements by looking at experiments. The given information will assist in looking at different elements, like solid, liquid and gas. This lesson will show examples to give a step by step explanation of spring analogy and better explain the concept.

This chemistry lesson is titled What Happens when Stuff Dissolves and will give a detailed explanation of the topic.

We'll learn how to determine the oxidation numbers or oxidation states for a the elements in a chemical compound. The oxidation numbers tell us how electrons are divided up or shared between atoms in a chemical compound. The oxidation numbers also tell us how electrons move in an oxidation reduction (redox) reaction. There are a set a rules that we use to determine oxidation number. Group 1A elements (alkalai metals) always have an oxidation of +1. Group 2A elements (alkaline earth metals) always have an oxidation number of +2. Elements on their own have an oxidation number of 0, and monatomic ions have an oxidation number that is equal to the ionic charge.

This is the first in a series of video lesson on d-block elements and their compounds. I look at the electronic configurations of the first row and try to explain the trend in their melting points. Minimizing electron repulsion is the most important consideration at play in these atoms and ions, but it is not the only one. This lesson is aimed at High School level and I only attempt to provide a simplified explanation. The following three points are perhaps worth adding: (1) the 4s orbital behaves as the outermost energy orbital - and as a result they nearly always lose a minimum of 2 electrons. (2) in addition to energy levels of orbitals, you need to factor in both their shape and closeness to one another - facilitating electron movements between them. (3) atomic orbitals can mix (hybridize) and at times the actual electronic configuration of the ions may be more complex than shown here.

This Chemistry lesson is titled Isotopes Notation and will give a detailed explanation of the topic.