STAAR Category 1

Front

How many protons are present in Hafnium (Hf) with a mass number of 178?

Back

72 protons

Front

An atom of an element has 36 protons, 36 electrons, and a mass number of 84. How many neutrons?

Back

48

Front

What types of particles are found in the cloud surrounding the atom's nucleus?
Options: positively and negatively charged particles , negatively charged particles only, neutral and positively charged particles, positively charged particles only

Back

negatively charged particles only

Front

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

Back

39

Front

What is the best description of an electron?

Back

Negative charge and much less mass than a proton.

Front

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

Back

+25

Front

Which statement accurately describes an atom of tin?

Back

tin atoms have 50 protons

Front

Atoms of a certain element have 11 protons and 1 valence electron. Which statement is correct?

Back

The element is sodium and it is highly reactive.

Front

What characteristic of an atom always determines its identity? Options: number of neutrons, number of protons, number of valence electrons, location of valence electrons

Back

number of protons

Front

Which characteristic of calcium is most closely related to its chemical reactivity?
Options: 20 protons in each calcium atom, calcium's density is 1.54 g.cm³, 2 valence electrons in each atom of calcium, one calcium atom has an atomic mass of 40.078 amu

Back

2 valence electrons in each atom of calcium