First 20 Elements Mastery

What is the symbol for the element with atomic number 8?

• He

• C

• H

• O

What is the electron configuration of the element with atomic number 12?

• 1s2 2s2 2p6 3s2 3p2

• 1s2 2s2 2p6 3s2

• 1s2 2s2 2p6 4s2

• 1s2 2s2 2p6 3s2 3d2

Which element has the highest atomic number in the first 20 elements?

• Calcium

• Oxygen

• Sodium

• Aluminum

What is the trend in atomic radius as you move from left to right across a period in the periodic table?

• The atomic radius decreases

• The atomic radius remains constant

• The atomic radius increases

• The atomic radius fluctuates

Which element in the first 20 has the highest electronegativity?

• Calcium (Ca)

• Potassium (K)

• Fluorine (F)

• Sodium (Na)

What is the physical state of the element with atomic number 2 at room temperature?

• gaseous

• solid

• liquid

• plasma

What is the chemical property of the element with atomic number 17?

• Low reactivity with metals

• High reactivity, especially with metals

• Stable under normal conditions

• Does not form compounds with other elements

What is the symbol for the element with atomic number 19?

• Hg

• Fe

• K

• Na

What is the electron configuration of the element with atomic number 16?

• 1s2 2s2 2p6 3s2 3p4

• 1s2 2s2 2p6 3s2 3p6

• 1s2 2s2 2p6 3s2 3p5

• 1s2 2s2 2p6 3s2 3p3

Which element in the first 20 has the lowest melting point?

• Nitrogen (N)

• Helium (He)

• Oxygen (O)

• Neon (Ne)