Chemical Valency & Formulae

How do you find an element's valency?

• Count the number of valence electrons in the outer shell

• Check if the compound is sour or sweet

• Look for the number of isotopes

• Weigh the element

What is a chemical formula?

• Symbolic representation of a chemical compound

• Biological process

• Physical constant

• Mathematical equation

Which of the following elements are known as the 'Alkali Metals' and have a valency of 1?

• Lithium, sodium, potassium, rubidium, cesium, francium

• Phosphorus, sulfur, chlorine

• Carbon, oxygen, nitrogen

• Iron, copper, zinc

Which of the following elements have a valency of 2?

• Oxygen, nitrogen, hydrogen

• Iron, copper, lead

• Magnesium, calcium, zinc, strontium, barium and radium

• Carbon, phosphorus, sulfur

Which of the following groups of elements have a valency of 3?

• Carbon (C), Silicon (Si), Selenium (Se)

• Oxygen (O), Fluorine (F), Chlorine (Cl)

• Iron (Fe), Manganese (Mn), Cobalt (Co)

• Boron (B), Aluminum (Al), Gallium (Ga), Indium (In), Thallium (Tl)

Which of the following elements have a valency of 4?

• Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs)

• Carbon (C), Silicon (Si), Germanium (Ge), Tin (Sn), Lead (Pb)

• Nitrogen (N), Phosphorus (P), Arsenic (As), Antimony (Sb)

• Oxygen (O), Fluorine (F), Chlorine (Cl), Bromine (Br)

Which of the following elements have a valency of 5?

• Elements of group 15 (according to the new numbering system) or group VA (according to the old numbering system)

• Elements of group 7

• Elements of group 18

• Elements of group 2

Which of the following elements have a valency of 6?

• Potassium (K), Boron (B), Helium (He)

• Oxygen (O), Selenium (Se), Tellurium (Te)

• Nitrogen (N), Phosphorus (P), Sulfur (S)

• Carbon (C), Fluorine (F), Sodium (Na)

Which of the following elements have a valency of 7?

• Oxygen (O), Sulfur (S), Phosphorus (P), Carbon (C)

• Nitrogen (N), Oxygen (O), Fluorine (F), Chlorine (Cl)

• Sodium (Na), Potassium (K), Lithium (Li), Rubidium (Rb)

• Fluorine (F), Chlorine (Cl), Bromine (Br), Iodine (I)

What are the elements known as the 'superheroes' of the periodic table with a valency of 8?

• Alkaline earth metals

• Halogens

• Noble gases

• Alkali metals