final exam Flashcards
Explain the differences between ionic and covalent compounds. Include element types, electron movement, and relative strength.
Ionic compounds are formed between a metal and a non-metal. The metal donates electrons to the non-metal, and in doing so, each becomes oppositely charged to the other. This creates a strong bond.
Covalent compounds are formed between two non-metals. Since the element types are the same, the valence electrons are shared – they spend their time equally between both atoms. This creates a weaker bond than ionic.
Describe the concept of pH. What does it mean? What is the involvement of hydrogen ions in determining the pH of something?
pH means “parts Hydrogen” – it is determined by the concentration of hydrogen ions in a solution. Because acids are hydrogen donors, when they are in solution, hydrogen ions are formed. The concentration of these hydrogen ions determines how acidic the solution is.
Explain how the pH scale is interpreted.
The pH scale covers a range of values from 0 to 14. The strong acids are at the lower end of the scale because they do not donate as many hydrogen ions to the solution. The strong bases are at the higher end of the scale because they result in a high concentration of hydroxide (OH-) ions when in solution.
The level 7 on the pH scale is neutral, because those substances result in equal balances of H+ and OH-.
What type of reaction is that which happens between magnesium and carbon dioxide? Explain.
Single displacement.
Magnesium is more strongly attracted to oxygen than is carbon. So, the Mg displaces the C and attaches itself to the O in the carbon dioxide.
Write the balanced chemical equation for the reaction of zinc + lead (II) nitrate –> zinc nitrate + lead
Zn + Pb(NO3)2 –> Zn(NO3)2 + Pb
Write the word equation for the following chemical equation:
Na3PO4 + CaCl2 –> Ca3(PO4)2 + NaCl
sodium phosphate + calcium chloride yields calcium phosphate + sodium chloride
What is the name of the chemical law that explains the need to balance all chemical equations? Describe the law.
The Law of Conservation of Mass.
In any reaction, the total mass of the products must equal the total mass of the reactants. No matter is lost.
If a chemical compound, such as NaCl is broken down into its element parts, what type of reaction has taken place?
Decomposition Reaction
Imagine a situation where two liquid (aqueous) chemicals are combined, and they react. One of the products is an insoluble compound (a solid). What is the term used to name this product?
Precipitate (tiny bits of insoluble product in a solution)
Summer is coming, and so are campfires. What type of reaction is taking place when the wood is burning? Write a word equation representing this reaction.
Burning material is a combustion reaction.
hydrocarbon + oxygen –> carbon dioxide + water + energy
Provide an explanation for why incandescent bulbs are inefficient sources of light when compared to other types of bulbs.
Incandescent bulbs are inefficient because much of the energy from the electric current is lost to heat and sound. The percentage of energy that is used in causing the filament to glow is less than 10%.
Why do the glow-in-the-dark star stickers pasted to the ceiling of the bio lab glow?
The material they are made from contains particles of phosphor that absorb the energy from UV light. They transmit that energy back as light.
Consider a plane mirror, and describe the relationship between the angle of incidence and the angle of reflection. You may use other terminology related to this scenario.
When reflecting off a plane mirror, light rays approach and leave the surface at equal angles. This is because the normal is perpendicular to the mirror’s surface – the angle of incidence is the angle between the incident ray (incoming light) and the normal. The angle of reflection is the angle between the reflected ray (reflected light) and the normal.
What acronym can be used to help remember the four characteristics of the properties of an image? List and describe/explain each property.
Acronym: SALT
S - size of image as compared to the object
A - attitude of image (its upright or inverted orientation as compared to the object)
L - location of the image (in front or behind)
T - type of image (real or virtual)
Explain how to accurately locate the virtual image of an object reflected in a plane mirror. Use correct terminology.
Because the distance from the object to the mirror is the same as the distance from the mirror to the virtual image, the line that joins them (the object-image line) is equidistant on either side of the mirror.
By choosing multiple points on the object, and creating object-image lines between them and their matching points on the image, one can map the exact position
