Chemistry: Seven Diatomic Elements Practice
Identifying and writing formulas for the seven elements that exist as diatomic molecules
Chemistry: Seven Diatomic Elements Practice
Identifying and writing formulas for the seven elements that exist as diatomic molecules
Chemistry - Grade 9-12
- 1
List the seven diatomic elements by name and write the correct chemical formula for each one.
The mnemonic BrINClHOF can help you remember bromine, iodine, nitrogen, chlorine, hydrogen, oxygen, and fluorine.
The seven diatomic elements are hydrogen, H2; nitrogen, N2; oxygen, O2; fluorine, F2; chlorine, Cl2; bromine, Br2; and iodine, I2. - 2
A student writes elemental oxygen as O in a chemical equation. Explain what is wrong and write the correct formula.
Elemental oxygen is diatomic, so it should be written as O2, not O. The correct formula shows that oxygen naturally exists as pairs of oxygen atoms. - 3
Circle or identify which formulas represent diatomic elements: H2, He, N2, Na, Cl2, CO2, Br2.
Only the seven special elements form diatomic molecules when they are alone in elemental form.
The formulas that represent diatomic elements are H2, N2, Cl2, and Br2. Helium, sodium, and carbon dioxide are not among the seven diatomic elements. - 4
Write the formula for elemental chlorine and explain why the subscript is needed.
Elemental chlorine is written as Cl2. The subscript 2 is needed because chlorine atoms pair together as diatomic molecules in their elemental form. - 5
Balance this equation for the formation of water: H2 + O2 -> H2O.
Do not change H2 or O2 into single atoms. Balance by adding coefficients in front of formulas.
The balanced equation is 2H2 + O2 -> 2H2O. This gives 4 hydrogen atoms and 2 oxygen atoms on both sides of the equation. - 6
Balance this equation for the formation of hydrogen chloride: H2 + Cl2 -> HCl.
The balanced equation is H2 + Cl2 -> 2HCl. There are 2 hydrogen atoms and 2 chlorine atoms on both sides. - 7
A periodic table diagram highlights hydrogen, nitrogen, oxygen, fluorine, chlorine, bromine, and iodine. What do these highlighted elements have in common?
Look for the elements that are written with a subscript 2 when they are alone.
They are the seven diatomic elements. In their elemental form, each exists as molecules made of two identical atoms. - 8
Decide whether each formula is correct for the element in its natural elemental form: F2, I, O2, Br, N2. Rewrite any incorrect formulas.
F2 is correct, I should be I2, O2 is correct, Br should be Br2, and N2 is correct. Iodine and bromine are diatomic elements, so their elemental formulas need a subscript 2. - 9
Explain the difference between the symbol N and the formula N2.
A chemical symbol can represent one atom, while a molecular formula can represent atoms bonded together.
N is the chemical symbol for one nitrogen atom. N2 is the formula for elemental nitrogen gas, which is made of two nitrogen atoms bonded together. - 10
Balance this equation for the formation of magnesium bromide: Mg + Br2 -> MgBr2.
The equation is already balanced as Mg + Br2 -> MgBr2. There is 1 magnesium atom and 2 bromine atoms on both sides. - 11
A student claims that all gases are diatomic elements. Use examples to explain why this claim is incorrect.
Think about noble gases such as helium, neon, and argon.
The claim is incorrect because only certain elements are diatomic in their elemental form. For example, oxygen gas is O2 and nitrogen gas is N2, but helium gas is He and is not diatomic. - 12
Classify each substance as a diatomic element, a monatomic element, or a compound: O2, Ne, H2O, Cl2, Na, CO2.
A diatomic element has two identical atoms. A compound contains two or more different elements.
O2 is a diatomic element, Ne is a monatomic element, H2O is a compound, Cl2 is a diatomic element, Na is a monatomic element, and CO2 is a compound.