Relative atomic mass
1. An element has two isotopes. One isotope has a mass number of 20 with
an abundance of 80%, and the other has a mass number of 22 with an
abundance of 20%. Calculate the relative atomic mass of the element.
2. An element has two isotopes: one with a mass number of 10 and an
abundance of 60%, and another with a mass number of 12 and an
abundance of 40%. Calculate the relative atomic mass of the element.
3. An element has three isotopes. The first isotope has a mass number of 23
with an abundance of 50%, the second has a mass number of 24 with an
abundance of 30%, and the third has a mass number of 25 with an
abundance of 20%. Calculate the relative atomic mass of the element.
4. An element consists of two isotopes. The first has a mass number of 28
and an abundance of 70%, while the second has a mass number of 30 and
an abundance of 30%. Calculate the relative atomic mass of the element.
5. An element has two isotopes. One isotope has a mass number of 35 with
an abundance of 60%, and the other has a mass number of 37 with an
abundance of 40%. Calculate the relative atomic mass of the element.
Law of constant proportion
1) Carbon and oxygen combine in the ratio of 3:8 by mass to form carbon
dioxide. What mass of oxygen gas would be required to react
completely with 6 grams of carbon?
2) An element X has an atomic number of 15 and a mass number of 30.
a) How many protons, neutrons, and electrons does it have?
b) Calculate the mass number of another isotope of if it has 16 neutrons.
c) Write its electronic configuration and identify its valency.
3) An atom of carbon has 6 protons and 6 neutrons.
a) What is the mass number of this atom?
b) If the atom gains 2 neutrons, what will be the new mass number?
4) An element has 11 electrons, 11 protons, and 12 neutrons.
a) Write its atomic number and mass number.
b) Write its electronic configuration.
c) Identify the element and its valency.
5) A) what is the mass number of an isotope of hydrogen that has 1 proton
and 2 neutrons?
b) An isotope of iodine has 53 protons and 78 neutrons. What is its mass
number?
7) An element has an atomic number of 9 and mass number 18.
a) Calculate the number of neutrons in the atom of element.
b) Write the electron distribution in this element.
c) What is the valency of this element?
7) An atom has 10 protons, 10 electrons, and 12 neutrons.
a) What is its mass number?
b) Write its atomic number.
c) What is its electron configuration?
8) A sodium ion has 10 electrons, 11 protons, and 12 neutrons.
a) What is the mass number of this ion?
b) What is the electron configuration of the sodium ion?
b) Why does sodium tend to lose one electron?
9) An element has 22 protons and 26 neutrons.
a) Calculate its mass number.
b) Identify the element and write its electronic configuration.
c) What is the number of valence electrons in this element?
10) An element has an atomic number of 16.
a) Write its electronic configuration.
b) Draw the Bohr model of this atom.
11) A) an element has 6 valence electrons. Write its valency.
b) Write the chemical formula of the compound formed when reacts with
hydrogen.
c) Another element has an atomic number of 13. What is its valency?
13) An atom of carbon has 6 protons and 6 neutrons.
a) What is the mass number of this atom?
b) If the atom gains 2 neutrons, what will be the new mass number?
