Elements

All atoms of the same element must have the same number of

• Protons

• Neutrons

• Compounds

• Electrons

An atom of the element zinc has an atomic number of 30 and a mass number of 65. How many protons does an uncharged zinc atom have?

• 30

• 35

• 65

• 95

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NGSS.MS-PS1-1

Scientists in a lab are working with two different samples of the element mercury. They know that the different samples are different isotopes. Which property of the isotopes must be different?

• the atomic number

• the electric charge

• the element name

• the mass number

When an atom that has no charge loses two electrons, it becomes a

• positive ion

• negative ion

• positive isotope

• negative isotope

A researcher is using a particle accelerator in an experiment studying isotopes. How can the researcher change one isotope into a different isotope of the same element?

• by adding valence electrons

• by removing valence electrons

• by adding and removing protons

• by adding and removing neutrons

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NGSS.HS-PS1-8

The symbol P represents the element phosphorus. This element’s atomic number is 15. How many protons and electrons are in a P–3 ion?

• 15 protons and 3 electrons

• 12 protons and 15 electrons

• 15 protons and 18 electrons

• 18 protons and 15 electrons

Tags

NGSS.MS-PS1-1

What can be added to an atom to cause a nonvalence electron in the atom to temporarily become a valence electron?

• energy

• mass

• neutrons

• electrons

The model below shows a carbide ion. What could be done to change this carbide ion to a neutral carbon atom?

• remove 2 electrons

• add 2 electrons

• remove 4 electrons

• add 4 electrons

Tags

NGSS.MS-PS1-1

Uranium is an element that is often used in nuclear power plants. Uranium atoms are very large, and the substance can be dangerous if it is not carefully contained.What is true about all uranium atoms?

• They each have the same number of nuclear particles

• They each have the same number of neutral particles.

• They each have the same number of neutrons.

• They each have the same number of protons.

One way in which elements differ from each other is the structure of the electron cloud in each element’s atoms. In an electron cloud, an electron that is farther away from the nucleus has

• a greater charge than an electron near the nucleus.

• a smaller charge than an electron near the nucleus

• a higher energy than an electron near the nucleus.

• a lower energy than an electron near the nucleus.

Tags

NGSS.HS-PS1-1