Balancing Equations
Balance this equation:
H₂ + O₂ → H₂O
2H₂ + O₂ → 2H₂O
The amount of a radioactive substance decreases by half during each of these.
What is a half-life?
This type of radiation consists of 2 protons and 2 neutrons.
What is alpha radiation?
This is the number of protons in an atom.
What is the atomic number?
A bond formed when atoms share electrons is called this.
What is a covalent bond?
Balance this equation:
N₂ + H₂ → NH₃
N₂ + 3H₂ → 2NH₃
If a sample has a half-life of 10 years, how much remains after 10 years if you start with 80 g?
What is 40 g?
This type of nuclear radiation is essentially a high-energy electron.
What is beta radiation?
Elements in this group are known as the noble gases.
What is Group 18?
A bond formed through the transfer of electrons, usually between a metal and a nonmetal, is called this.
What is an ionic bond?
Balance this equation:
Fe + O₂ → Fe₂O₃
4Fe + 3O₂ → 2Fe₂O₃
A radioactive isotope has a half-life of 5 days. What fraction remains after 15 days?
What is ⅛ (12.5%)?
This type of radiation has no mass and no charge and consists of high-energy electromagnetic radiation.
What is gamma radiation?
This element has the atomic number 17.
What is chlorine (Cl)?
This type of covalent bond occurs when electrons are shared unequally between atoms.
What is a polar covalent bond?
Balance this combustion reaction:
C₃H₈ + O₂ → CO₂ + H₂O
C₃H₈ + 5O₂ → 3CO₂ + 4H₂O
A sample starts with 160 g and has a half-life of 4 hours. How much remains after 12 hours?
What is 20 g?
During alpha decay, an atom's atomic number decreases by this amount and its mass number decreases by this amount.
What are 2 and 4, respectively?
As you move from left to right across a period, atomic radius generally does this.
What is decreases?
In NaCl, sodium becomes this type of ion after losing an electron.
What is a cation (Na⁺)?
Balance this equation:
Al + HCl → AlCl₃ + H₂
2Al + 6HCl → 2AlCl₃ + 3H₂
A radioactive sample has 6.25% of its original material remaining. If its half-life is 8 years, how much time has passed?
What is 32 years?
(6.25% = 1/16 = 4 half-lives.)
Uranium-238 undergoes alpha decay. What daughter isotope is produced?
What is Thorium-234 (²³⁴Th)?
This element is in Period 3, Group 2 and commonly forms a +2 ion.
What is magnesium (Mg)?
Which molecule contains a triple covalent bond: H₂O, CO₂, N₂, or CH₄?
What is N₂?