chemp/phys

If 2 grams of element X combine with 4 grams of element Y to form compound XY, how many grams of element Y would combine with 14 grams of X to form the same compound?

28 grams

Which statement about subatomic particles is true?

An electron has far less mass than either a proton or neutron.

Which statement about electrons and atomic orbitals is NOT true?

An electron has the same amount of energy in all orbitals.

Which statement accurately represents the arrangement of electrons in Bohr's atomic model?

Electrons travel around the nucleus in fixed energy levels with energies that vary from level to level.

Who provided evidence for the existence of a nucleus in an atom?

Ernest Rutherford

How was Bohr's atomic model similar to Rutherford's model?

It described a nucleus surrounded by a large volume of space.

Which statement best describes Rutherford's model of the atom?

It is like a huge stadium with a positively charged marble at the center.

Which statement about subatomic particles is NOT true?

Protons and neutrons have the same charge.

What is the difference between an atom in the ground state and an atom in an excited state?

The atom in the ground state has less energy and is less stable than the atom in an excited state.

What can you assume has happened if an electron moves to a higher energy level?

The electron has gained energy.

Suppose an atom has a mass number of 23. Which statement is true beyond any doubt?

The number of protons in the nucleus does not equal the number of neutrons.

Which statement is true about oxygen-17 and oxygen-18?

Their atoms have an identical mass.

Rutherford's gold foil experiment provided evidence for which of the following statements?

There is a dense, positively charged mass in the center of an atom.

Which of the following provides the best analogy for an electron in an atomic orbital?

a bee trying to escape from a closed jar

Which of the following most accurately represents John Dalton's model of the atom?

a tiny, solid sphere with a predictable mass for a given element

The Greek philosopher Democritus coined what word for a tiny piece of matter that cannot be divided?

atom

To find the number of neutrons in an atom, you would subtract

atomic number from mass number.

The number of protons in one atom of an element is that element's

atomic number.

In an atomic model that includes a nucleus, positive charge is

concentrated in the center of an atom.

J. J. Thomson's experiments provided evidence that an atom

contains negatively charged particles.

Which subatomic particle has a negative charge?

electron

In Niels Bohr's model of the atom, electrons move

like planets orbiting the sun.

The glowing of a neon light is caused by electrons emitting energy as they

move from higher to lower energy levels.

What do scientists use to predict the locations of electrons in atoms?

probability

Democritus thought that matter was made of tiny particles

that could not be divided.

What does the electron cloud model describe?

the most likely locations of electrons in atoms

Which of the following is unique for any given element?

the number of protons

According to John Dalton's observations, when elements combine in a compound,

the ratio of their masses is always the same.