Atomic Structure Quiz

What particles are found in the nucleus of an atom?

• Protons and neutrons

• Electrons and protons

• Electrons and neutrons

• Electrons only

Answer explanation

The nucleus of an atom contains protons and neutrons. Protons are positively charged, while neutrons have no charge. Electrons, which are negatively charged, orbit the nucleus but are not found within it.

Tags

NGSS.HS-PS1-8

Which scientist is known for the discovery of the electron?

• J.J. Thomson

• Ernest Rutherford

• Niels Bohr

• Dmitri Mendeleev

Answer explanation

J.J. Thomson is credited with the discovery of the electron in 1897 through his experiments with cathode rays, demonstrating that they were composed of negatively charged particles, which he named electrons.

What is the smallest unit of an element?

• Atom

• Molecule

• Compound

• Electron

Answer explanation

The smallest unit of an element is an atom. Atoms consist of protons, neutrons, and electrons, and they combine to form molecules and compounds. Therefore, the correct answer is 'Atom'.

Which element has an atomic number of 1?

• Hydrogen

• Helium

• Oxygen

• Carbon

Answer explanation

The element with an atomic number of 1 is Hydrogen. It is the simplest and most abundant element in the universe, consisting of one proton and one electron.

What does the atomic number of an element represent?

• Number of protons

• Number of neutrons

• Total mass

• Number of electrons in the nucleus

Answer explanation

The atomic number of an element represents the number of protons in its nucleus. This number determines the element's identity and its position in the periodic table.

What is the charge of an electron?

• Negative

• Positive

• Neutral

• It varies

Answer explanation

The charge of an electron is negative, which is a fundamental property of this subatomic particle. This negative charge is what allows electrons to interact with positively charged protons in atoms.

Tags

NGSS.HS-PS2-4

Which of these best describes a compound?

• A substance made of two or more elements chemically combined

• A single atom

• A group of identical atoms

• A random mixture of elements

Answer explanation

A compound is defined as a substance formed when two or more elements are chemically combined. This distinguishes it from single atoms, groups of identical atoms, or random mixtures, making the first choice the correct answer.

Tags

NGSS.5-PS1-4

How did the discovery of the nucleus change atomic theory?

• It showed that atoms have a dense center

• It proved atoms are indivisible

• It showed atoms are entirely hollow

• It suggested atoms could not have electrons

Answer explanation

The discovery of the nucleus revealed that atoms have a dense center, fundamentally changing atomic theory by introducing the idea of a central core, which contradicted the earlier notion of atoms being indivisible or hollow.

Tags

NGSS.HS-PS1-8

Which of these scientists developed the first atomic theory?

• John Dalton

• Albert Einstein

• Marie Curie

• James Chadwick

Answer explanation

John Dalton is credited with developing the first atomic theory in the early 19th century, proposing that matter is made up of indivisible atoms. His work laid the foundation for modern chemistry.

What model describes electrons orbiting in fixed paths?

• Bohr model

• Quantum model

• Plum pudding model

• Thomson model

Answer explanation

The Bohr model describes electrons orbiting the nucleus in fixed paths or orbits, each with a specific energy level. This model was a significant advancement in understanding atomic structure compared to earlier models.