Which have different numbers of electrons?
This is how manganese appears in the periodic table.

While looking at bromine (Br) on the periodic table, a student needs to find another element with very similar chemical properties but with a different atomic mass. Which best describes the student’s options?
An atomic physicist determines that an atom is composed of 8 positively charged particles and has a mass of 15 amu. Which is the best conclusion that can be drawn?
The model below shows an atom of an element.

The atomic number of beryllium (Be) is 4, and the atomic number of barium (Ba) is 56. Which comparison is best supported by this information?
Particle A has very little mass in comparison to Particle B. Both particles are in the same atom. Which is the best conclusion about Particles A and B?
What is an atomic nucleus?
Who was the first chemist to organize elements by atomic number?
What is the electron configuration for helium (He)?
Which shows the electron configuration for Silicon (Si)?
Students are completing a table about a particular subatomic particle that helps make up an atom.What best explains how they should complete the table?

Scientists have changed the model of the atom as they have gathered new evidence. One of the atomic models is shown below.

An atom of the element chromium has an atomic number of 24 and a mass number of 52. How many electrons are in an uncharged atom of chromium?
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