Chemistry 2019 Final Review Questions
How many electrons are in the outermost energy shell of a calcium atom?
2
What is the atomic mass of silicon?
28.1
How many different elements are in the compound sodium carbonate (Na2CO3)?
3
How many protons are in an atom of bromine?
35
What is the atomic number of carbon-14?
6
This balanced equation represents a chemical reaction. 2C4H10(g)+13O2(g)➡️8CO2(g)+10H2O(g) What type of chemical reaction is represented by the equation?
Combustion
Why is the compound sodium chloride stable?
Sodium loses one electron and chlorine gains one electron
A teaspoon of dry coffee crystals dissolved when mixed in a cup of hot water. This process produces a coffee solution. The original crystals are classified as a...
Solute
Which of the following atoms has six valence electrons?
Sulfur (S)
Consider this reaction: NH3(g)+HCl(g)➡️NH4Cl(s) Which type of reaction does this equation represent?
Synthesis
A student is given a sample of an unknown liquid to test in a laboratory. Which of the following physical properties will be most useful to determine if the liquid is water?
boiling point of a liquid
When cations and anions join, they form what kind of chemical bond?
ionic
What is the smallest unit of a chemical compound that still has the properties of that compound?
molecule
When magnesium (Mg) metal is burned in the presence of oxygen (O2), magnesium oxide (MgO) is produced. The properties of magnesium oxide are different than the individual properties of magnesium and oxygen because magnesium oxide is...
A compound
Which of the following best describes an atom?
A core or protons and neutrons surrounded by electrons
Which of the following is a characteristic of all chemical changes?
A new material is formed
An element located at group 18 and period 4 would be classified as which type of substance?
A nonmetal
Solutions of lead(II) nitrate and potassium dichromate are mixed. The solution turns cloudy and yellow. Solid yellow particles fall to the bottom of the beaker. Which statement best describes this reaction?
A precipitate formed
Which of the following represents a double displacement reaction?
AB+CD➡️AD+CB
The smallest particle of any element that still has properties of that element is called...
An atom
When a chemical cold pack is activated, it becomes cool to the touch. What is happening in terms of energy?
An endothermic reaction is occurring, absorbing heat from its surroundings
What is the smallest particle of the element gold (Au) that can still be classified as gold?
Atom
What do all atoms of the same element have in common?
Atomic number
Which of the following chemical reactions is a decomposition reaction?
BaCO3➡️BaO+CO2
Which of the following atoms has the largest atomic radius?
Barium (Ba)
According to the periodic table, the neutral atom of what element has 4 protons, 5 neutrons, and 4 electrons?
Beryllium
Based on its position on the periodic table, which of the following elements is a nonmetal?
Bromine (Br)
Which molecule represents an element?
Bromine gas (Br2)
Which of the following is an example of a chemical change?
Burning a scented candle
Which element is an alkaline earth metal?
Ca
Which equation represents a double replacement reaction?
CaBr2+Na2CO3➡️CaCO3+2NaBr
Which of the following is best classified as a compound?
Carbon dioxide (CO2), because it contains two different types of atoms
Which of the following elements is a member of the halogen family and is located in period 3?
Chlorine
Which two elements have the same number of valence electrons?
Cl and F
When pure N2O5 is heated under certain conditions, O2 and NO2 are produced. What type of reaction is this?
Decomposition
Which of the following is found farthest from the center of an atom?
Electron
Which of the following trends in the periodic table should be expected as the atomic number of the halogens increases from fluorine (F) to iodine (I)?
Electronegativity decreases
Which of the following statements describes an exothermic reaction but not an endothermic reaction?
Energy is released as heat during the reaction
A balanced chemical equation reflects the idea that the mass of the products...
Equals the mass of the reactants
Which of the following elements is a nonmetal?
Fluorine
Which is the best example of a pure substance?
Gold
Which of the following sections of the periodic table contains only metals?
Group 2
Which of the following is an example of nuclear fusion?
Hydrogen-1 and hydrogen-2 combine to form helium-3
Which two substances are elements?
Iron and helium
Which of the following explains why saltwater is considered a mixture?
It is composed of two or more substances that retain their own chemical properties
In which of the following lists are the elements shown in order of increasing electronegativity?
Li, Be, O, F
Which of the following elements is classified as a metal?
Lithium
The periodic table of elements is arranged so that elements with similar characteristics are in the same column. Which element is a highly reactive metal?
Magnesium (Mg)
Which of these is an example of a physical change?
Melting ice
Which class of elements best conducts electricity?
Metals
Using the periodic table, which sentence about the periodic table of elements is true?
Metals are found on the left side of the periodic table
Magnesium has two valence electrons. Oxygen has six valence electrons. What is the correct chemical formula for magnesium oxide?
MgO
Which is an example of a chemical reaction?
Nails rusting
Which is responsible for producing heat and light from the sun?
Nuclear energy
How do the atoms of carbon-12 and carbon-14 differ?
Number of neutrons
Which of the following is the most important factor in determining an elements place in the periodic table?
Number of protons
Which of the following is the same for both hydrogen and potassium?
Number of valence electrons
Group 1 (the alkali metals) includes lithium (Li), sodium (Na), and potassium (K). These elements have similar chemical properties because they have the same ______________.
Numbers of electrons in the outer energy level
The atomic number of protons is 6, which means that carbon atoms always have 6_________.
Protons
Which of the following subatomic particles can be could inside the nucleus of an atom?
Protons and neutrons
Which of the following colors of visible light has the longest wavelength?
Red
Which of the following elements is a metalloid?
Silicon
Which elements are in the same period?
Silver and tin
What do the elements sulfur (S), nitrogen (N), phosphorous (P), and bromine (Br) have in common?
They are nonmetals
Which of the following statements describes the elements in family 16 of the periodic table?
They have 6 valence electrons
Which pure substance is composed of more than one element?
Water
What causes an object to have a positive charge?
electrons are removed
