Lesson Plan - Get It!
Here is a question to keep you awake at night: How would nature be different if elements were unable to bond?
This lesson allows you to review how elements bond in a variety of ways by sharing and transferring electrons between atoms.
Sometimes, the compound even creates a sea of unbonded electrons, able to conduct electricity and heat. Each type of bond has unique characteristics based on how the elements interact.
- For example, how are covalent and ionic bonds different?
The ability of an element to bond is based on the electrons found in the atomic nucleus. Elements have a specific number of valence electrons, held in the outer shell of the nucleus.
These electrons are responsible for allowing the atom to bond. Electron configurations can be used to map the electrons for each element on the periodic table. This helps identify where electrons can be found in an atom, and how many valence electrons the atom has. The electron configuration is based on the shape of the orbitals found in the elemental atom.
- To review, what does an electron configuration show you?
Remember that "s" orbitals can only hold two electrons, while "p-shaped" orbitals can hold six. "D" orbitals can hold ten electrons. Each of these orbitals is used in an electron configuration to depict the location of electrons.
- Why do you think each orbital can hold a specific number of electrons?
When an element has electrons in the outer shell, it is able to bond with other elements. There are three types of chemical bonds: covalent, ionic, and metallic. In a covalent bond, electrons are shared between two atoms. Covalent bonds involve nonmetals, like oxygen and carbon. Ionic bonds form when electrons are transferred from a metallic element to a nonmetal. An example is sodium chloride, where the electrons are moved from sodium to chlorine. Metallic compounds use free-flowing electrons to conduct electricity and heat easily.
- What is the difference between a chemical and physical change?
Elements and compounds can experience physical and chemical changes in the environment. A physical change modifies the shape or size of the substance, while chemical changes actually affect the chemical composition of the material. An example is baking a cake — mixing the flour and sugar would be physical change, but exposing batter to high heat would produce a chemical change.
Review the law of conservation of mass.
- How is this natural law shown in chemical equations?
In every chemical reaction or change, mass is conserved. The law of conservation of mass states that matter cannot be created or destroyed. This means that the amount of matter on Earth is constant, but that it can change forms. The conservation of matter, or mass, is represented by balancing chemical reactions, so you have the same number of each element on both the reactant and product side of the reaction.
Try to name the chemical reactions you learned about in previous lessons. Chemical reactions show how elements and compounds bond and interact.
There are five types of chemical reactions: synthesis, decomposition, single replacement, double replacement, and combustion.
Synthesis reactions involve two reactants combining into a single product, and decomposition is the opposite. In a decomposition reaction, a single reactant breaks down into two products. A single replacement reaction involves a compound and a free element. The free element tries to displace a component of the compound, but you have to check the reactivity series to be sure that the element can be replaced.
In a double replacement reaction, both compounds are blended and mixed. It is important that a precipitate, or a solid, forms during this reaction. Remember to read the solubility rules to ensure that a solid is able to form.
Finally, combustion reactions all end up with carbon dioxide and water as products. Combustion involves mixing a substance with pure oxygen, often creating a flame or explosion.
Combustion is an example of an exothermic reaction, because heat and light are released as energy. An endothermic reaction occurs when the substances absorb energy from the environment and actually get colder.
Each type of chemical reaction has a special role on the planet. Some provide plants with energy from sunlight. Photosynthesis is a great example of an endothermic reaction, but it also uses complex chemical reactions to change reactants into glucose! Combustion reactions power our cars, but can be challenging to balance.
Every element on the planet has electrons organized around a central nucleus, able to be mapped using a configuration calculated using the periodic table. The valence electrons in the outer layer of the atom are responsible for determining what type of chemical bond forms. Chemical bonding occurs in your daily life as you ride in your car to the grocery store and prepare your dinner. When you clean your bathroom, you are relying on chemical reactions to break down the grime and dirt!
In the Got It? section, you will watch a video to review ideas related to bonding and reactions.