What does the atomic number of an element represent?

• The number of protons in the nucleus of an atom

• The sum of protons and neutrons in the nucleus

• The number of electrons in the outermost energy level

• The one or two-letter abbreviation of the element's name

What determines the chemical properties and reactivity of an element?

• The number of valence electrons

• The atomic symbol

• The mass number

• The number of protons

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

Which theory helps predict the shape of a molecule based on the repulsion between electron pairs?

• VSEPR theory

• Atomic theory

• Quantum theory

• Relativity theory

What is the shape of a molecule with a central atom that has four valence electrons, like carbon?

• Tetrahedral

• Linear

• Bent

• Trigonal planar

What unique property of water is influenced by its molecular geometry?

• High surface tension

• Low boiling point

• Inability to dissolve substances

• High density

What is the sum of protons and neutrons in the nucleus of an atom called?

• Mass number

• Atomic number

• Valence number

• Electron number

Tags

NGSS.HS-PS1-8

Which type of molecular geometry does oxygen often form in molecules like water?

• Bent

• Linear

• Tetrahedral

• Trigonal planar

Electrons in the outermost energy level are called _____ electrons

Tags

NGSS.HS-PS1-1