Understanding the Periodic Law

What is the primary focus of the periodic law?

• The origin of chemical reactions

• The development of the modern periodic table

• The discovery of new elements

• The classification of compounds

Who proposed the early periodic table?

• Isaac Newton

• Albert Einstein

• Dmitri Mendeleev

• Marie Curie

How did Mendeleev arrange the elements in his periodic table?

• By increasing atomic mass

• By decreasing atomic mass

• Alphabetically

• By increasing atomic number

Which elements were found to have similar properties in Mendeleev's table?

• Hydrogen and Helium

• Lithium and Sodium

• Nitrogen and Neon

• Carbon and Oxygen

What pattern did Mendeleev observe in the properties of elements?

• A constant decrease

• A linear increase

• A random distribution

• A periodic recurrence

How were the rows and columns arranged in Mendeleev's table?

• Rows by atomic number, columns by mass

• Rows and columns by atomic number

• Rows by mass, columns by similar properties

• Rows by similar properties, columns by mass

What is a key difference between Mendeleev's table and the modern periodic table?

• The modern table is arranged alphabetically

• The modern table has fewer elements

• The modern table uses atomic number

• The modern table uses atomic mass

How many elements are known today compared to Mendeleev's time?

• 65 elements today

• 119 elements in Mendeleev's time

• 119 elements today

• 65 elements in modern times

What determines the order of elements in the modern periodic table?

• Chemical reactivity

• Atomic number

• Alphabetical order

• Atomic mass

Why do elements in the same column of the modern periodic table have similar properties?

• They have the same atomic mass

• They are in the same period

• They have the same number of protons

• They have similar electron configurations