Practice Regents - Multiple Choice

Which statement describes the earliest model of the atom?

• An atom is an indivisible hard sphere.

• An atom has a small, dense nucleus.

• Electrons are negative particles in an atom.

• Electrons in an atom have wave-like properties.

Answer explanation

Earliest models were the most basic models!

In all atoms of bismuth, the number of electrons must equal the

• number of protons

• number of neutrons

• sum of the number of neutrons and protons

• difference between the number of neutrons and protons

Answer explanation

ATOMS are electrically neutral. Meaning Protons=Electrons.

Tags

NGSS.HS-PS1-7

Which symbol represents a particle that has a mass approximately equal to the mass of a neutron?

• α

• β−

• β+

• p

Answer explanation

Table O will tell you the masses (top left number), protons and neutrons both equal 1 amu (u is also used as a unit for subatomic particles).

An orbital is a region in an atom where there is a high probability of finding

• an alpha particle

• an electron

• a neutron

• a positron

Answer explanation

Definition question! You HAVE to know the definition of an orbital. It almost always shows up as a question on the Regents.

Which electron shell in an atom of calcium in the ground state has an electron with the greatest amount of energy?

• 1

• 2

• 3

• 4

Answer explanation

Electrons increase in energy away from the nucleus. Like a kid at an amusement park: Away from Mom (nucleus), that kid (electron) is getting into trouble. But, close to Mom, they are kept under control. Low energy.

Tags

NGSS.HS-PS1-1

As the elements in Period 2 are considered in order from lithium to fluorine, there is an increase in the

• atomic radius

• electronegativity

• number of electron shells

• number of electrons in the first shell

Answer explanation

Use Table S! It LITERALLY has electronegativity values for you to compare. Fluorine has the highest e-neg.

Tags

NGSS.HS-PS1-1

Which element is classified as a metalloid?

• boron

• potassium

• sulfur

• xenon

Answer explanation

Follow the bolded, stair-case line on the periodic table. Any element touching that is a metalloid, EXCEPT...Aluminum.

Strontium and barium have similar chemical properties because atoms of these elements have the same number of

• protons

• neutrons

• electron shells

• valence electrons

Answer explanation

They are in the same group, thus the same number of valence. Valence electrons dictate properties.

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

Which term represents the fixed proportion of elements in a compound?

• atomic mass

• molar mass

• chemical formula

• density formula

Answer explanation

If you add an oxygen to H₂O, is it still water? NO! Its H₂O₂ and that would suck to drink. Compounds have a fixed proportion, which you cannot change without changing the element.

Which two terms represent types of chemical formulas?

• molecular and structural

• mechanical and thermal

• molecular and structural

• molecular and thermal

Answer explanation

Molecular, structural, and empirical are the three types of chemical formulas.

Molecular = Shows exactly what is in a compound (ex. CH₄).

Empirical = Lowest ratio of elements in a compound: C₆H₁₂O₆ --> C₁H₂O₁

Structural = Shows how the atoms are bonded and arranged.