Chem and Water Quiz

What to know...

  • Basic atomic structure

  • Be familiar with common elements on the periodic table. 

  • ions

  • compounds

  • valence electrons

  • isotopes

  • pH scale - know the pH of some typical household items. 

    • what are buffers and how do buffers work

  • structure and polarity of water molecules

  • properties of water

  1. Atomic structure

    • extremely small, positively charged nucleus surrounded by a cloud of negatively charged electrons

    • protons, neutrons and electrons

  2. Common elements on the table

    • Hydrogen (H)

    • Helium (He)

    • Carbon (C)

    • Oxygen (O)

    • Nitrogen (N)

    • Sodium (Na)

    • Aluminum (Al)

    • Potassium (K)

  3. Ions

    What is a ion? - an atom or group of atoms that carries a positive or negative electric charge as a result of having lost or gained one or more electrons

  4. Compounds

    Definition: A substance made from two or more different elements that have been chemically joined. Examples of compounds include water (H2O), which is made from the elements hydrogen and oxygen, and table salt (NaCl), which is made from the elements sodium and chloride.

  5. Valence Electron

    What is it? - Valence electrons are electrons in the outermost shell of an atom, and that can participate in the formation of a chemical bond if the outermost shell is not closed

    Examples - Examples include hydrogen (H), lithium (Li), and sodium (Na). Any element in group 18 has eight valence electrons (except for helium, which has a total of just two electrons). Examples include neon (Ne), argon (Ar), and krypton (Kr). Oxygen, like all the other elements in group 16, has six valence electrons.

  6. Isotopes

    What are Isotopes? - Isotopes are when a form of chemical element in which the atoms have the same number of protons but different number of neutrons. They share almost the same chemical properties, but differ in mass and therefore in physical properties. There are stable isotopes, which do not emit radiation, and there are unstable isotopes, which do emit radiation. The latter are called radioisotopes.

  7. pH Scale

    • What is it? - The pH scale measures how acidic an object is. Objects that are not very acidic are called basic. The scale has values ranging from zero (the most acidic) to 14 (the most basic).

    • pH stands for “Potential of Hydrogen.” This term represents the hydrogen ions (H+) concentration in a solution

      • BUFFER - A buffer is a solution that can resist pH change upon the addition of an acidic or basic components. It is able to neutralize small amounts of added acid or base, thus maintaining the pH of the solution relatively stable

    • Everyday home objects and their pH scale.

      1. Apples, 3, acidic

      2. Bananas, 4, acidic

      3. Borax, 9, basic

      4. Water, 7, Neutral

  8. Structure and Polarity of Water Molecules

    • Oxygen has a high electronegativity compared to hydrogen resulting in water molecule having polarity

    • Polarity allows molecules to form hydrogen bonds when oppositely charged region of two molecules interact

    • The term cohesion refers to molecules of the same type forming hydrogen bonds with another and adhesion refers to different types of molecules forming hydrogen bonds with one another

    • Living systems depending upon water properties, like surface tension

      • Polar = A structure having an uneven distribution of electron density'

      • Non-polar = Molecules that do not have any electrical charges or partial charge

      • Solubility = degree to which a substance dissolves in a solvent to make a solution

        NON-POLARPOLAR

  9. Properties of Water (similar to above)

    • COHESION = Cohesion is the act, state, or process of sticking together of like molecules or entities

    • SURFACE TENSION = The property of the surface of a liquid that allows it to resist an external force, due to the cohesive nature of its molecules

    • ADHESION = The binding of two or more cells together or the binding of a cell to a surfaces

      CAPILLARY ACTION = It is the movement of a liquid through or along another material against an opposing force, such as gravity

    • DENSITY OF WATER = It is the movement of a liquid through or along another material against an opposing force, such as gravity

    • HIGH HEAT CAPACITY = One of water's most significant properties is that it takes a lot of energy to heat it