STAAR Matter Practice

Which statement accurately describes the atoms of a specific element?

• An Indium, In, Atom contains 115 protons inside the nucleus and 49 neutrons outside the nucleus.

• A scandium, Sc, atom contain 45 electrons outside the nucleus and 21 neutrons inside the nucleus.

• An aluminum, Al, atom contains 27 electrons and 27 protons inside the nucleus.

• A zinc, Zn, atom contain 30 protons inside the nucleus and 30 electrons outside the nucleus.

Tags

NGSS.MS-PS1-1

Which statement correctly describes the location and charge of the electrons in an atom?

• The electrons are inside the nucleus and have no charge.

• The electrons are outside the nucleus and have no charge.

• The electrons are inside the nucleus and have a negative charge.

• The electrons are outside the nucleus and have a negative charge.

What is the total number of protons, neutrons, and electrons in a cadmium, Cd, atom that has a mass number of 112?

• 160

• 112

• 48

• 64

What is the difference between the number of electrons in an atom of selenium, Se, and the number of electrons of aluminum, Al?

• 21

• 52

• 13

• 34

An atom of a certain element has 36 protons, 36 electrons, and a mass number of 84. At room temperature this element is a very stable gas. How many neutrons are in this atom?

• 48

• 84

• 72

• 36

Tags

NGSS.MS-PS1-1

In the early 1900s many scientists thought that an atom consisted of a positive substance with negative charges scattered throughout the substance. Then Ernest Rutherford completed an experiment that changed the concept of the atom. His discovery led to the understanding that an atom consists mostly of empty space with -

• protons orbiting a dense nucleus made of electrons and neutrons

• electrons orbiting a dense nucleus made of protons and neutrons

• neutrons and protons orbiting a cloud of electrons

• electrons and protons orbiting a cloud of neutrons

Tags

NGSS.HS-PS1-8

A model of a beryllium atom is shown below.

What type of particles are found in the cloud surrounding the atom's nucleus?

• Positively charges particles and negatively charges particles

• Negatively charged particles only

• Neutral particles and positively charges particles

• Positively charges particles only

Tags

NGSS.MS-PS1-1

What is the mass number of a potassium (K) atom that has 20 neutrons?

• 18

• 19

• 20

• 39

Which of the following best describes an electron?

• It has no charge and about the same mass as a proton.

• It has a negative charge and much less mass than a proton.

• It has a positive charge and much more mass than a neutron.

• It has a negative charge and about the same mass as a neutron.

Tags

NGSS.MS-PS2-3

An atom has 25 protons, 30 neutrons, and 25 electrons. What is the charge of the atom's nucleus?

• +25

• +30

• -25

• -30