What is an Atom?

Atoms are the fundamental building blocks of all matter, incredibly small and numerous. They can be visualized using powerful electron microscopes, revealing their distinct structures. Atoms consist of protons, neutrons, and electrons, with most of the atom being empty space. The nucleus, containing protons and neutrons, is dense and accounts for most of the atom's mass. Electrons orbit the nucleus, balancing the positive charge of protons. The atomic number, determined by the number of protons, defines an element's identity and influences its reactivity. Despite their minuscule size, atoms form the basis of everything around us.

What is the approximate size of an atom?

• 1 tenth of a millionth of a millimeter

• 1 tenth of a millimeter

• 1 millimeter

• 1 millionth of a millimeter

Which subatomic particle is positively charged?

• Electron

• Proton

• Nucleus

• Neutron

What is the role of electrons in an atom?

• They are located in the nucleus

• They carry a positive charge

• They orbit the nucleus and balance the positive charge of protons

• They determine the atom's mass

What does the atomic number of an element represent?

• The number of protons

• The total mass of the atom

• The number of electrons

• The number of neutrons

How does the atomic number influence an element's reactivity?

• It affects the number of protons

• It changes the atom's mass

• It determines the number of neutrons

• It influences the number of electrons, which affects reactivity