WorksheetsTopic 1- The Atom Chemistry Regents 2025
Total questions: 44
Worksheet time: 4hrs 41mins
The basic unit of matter is called the:
atom
subatomic particles
nucleus
energy shell
The acronym amu stands for:
Atomic mass unit
Atomic molar unit
Atomic milli unit
Atomic mass
How many neutrons are in the nucleus of an atom with an atomic number of 26?
30 neutrons
29 neutrons
31 neutrons
26 neutrons
State the atomic mass of oxygen (round to the nearest whole number).
16u
8u
5u
15u
Which of the following chemical symbols is correctly paired with its chemical element? Check ONLY THE CORRECT boxes.
He- Helium
O- Oxygen
K- Potassium
C- Chlorine
N- Neon
If the atomic number of an atom in ground state is 9, determine the number of protons, neutrons, and electrons.
9 protons, 9 electrons, and 10 neutrons.
9 protons, 9 electrons, and 9 neutrons.
10 protons, 9 electrons, and 9 neutrons.
9 protons, 9 electrons, and 19 neutrons.
Which of the following choices is correct regarding amu? Check ONLY THE CORRECT boxes.
Proton = 1 amu
Neutron = 1 amu
Electron = 0 amu
Neutron = 0 amu
Electron = 1 amu
Which of the following choices is correct regarding charges? Check ONLY THE CORRECT boxes.
Proton = positive
Neutron = neutral
Electron = negative
Neutron = negative
Electron = neutral
The gold-foil experiment from Rutherford states that the:
positively charged nucleus is both dense and small. Also, the atom is made of mostly empty space.
proton is large and located in the electron shell.
electron is located in both the nucleus and energy level.
proton and neutron are large and located in the electron shell.
If the atomic number of an atom in ground state is 35, determine the number of protons, neutrons, and electrons.
35 protons, 35 electrons, and 45 neutrons.
35 protons, 35 electrons, and 44 neutrons.
35 protons, 35 electrons, and 46 neutrons.
35 protons, 35 electrons, and 35 neutrons.
Atoms that have the same number of protons but a different number of neutrons are known as (just type your one word answer):
(a)
What is the atomic mass number of an atom with 9 protons, 10 neutrons, and 9 electrons?
19 amu
9 amu
18 amu
28 amu
A chemist is most likely to find ______& ________ in the nucleus of an argon atom.
protons & neutrons
protons & electrons
electrons & neutrons
protons, neutrons, and electrons
Type only the chemical name of the atom that has an atomic number of 19.
(a)
The wave-mechanical model states that an orbital is the most probable location of an:
electron
atom
proton
neutron
Rutherford's gold-foil experiment states that the nucleus:
is dense and positive, and the atom is mostly empty space.
contains a small percentage of mass of an atom.
has no charge.
has a negative charge.
Evidence indicates that the nucleus of an atom is most likely:
positively charged
negatively charged
neutrally charged
Using the diagram, which particle remains undeflected when passing through the field.
proton
neutron
electron
atom
The total mass number of protons and neutrons in the nuclide (nucleus) of S-33 is
16
33
32
17
The number of neutrons for Al-28 is:
14
15
13
27
A neutral atom with 6 electrons and 8 neutrons is an isotope of:
carbon
silicon
nitrogen
oxygen
The discovery of the electron as a subatomic particle was a result of:
experiments with cathode ray tubes
experiments with atoms and positively charged nuclei
the gold foil experiment
an atom that is indivisible and considered a hard sphere
The earliest model of the atom is best described as:
experiments with cathode ray tubes
experiments with atoms and positively charged nuclei
the gold foil experiment
being an indivisible hard sphere
C-12, C-13, and C-14 are all examples of
different atoms
naturally occurring isotopes
atoms with the same number protons and neutrons
atoms with the same number of neutrons but different number of protons
The weighted average of the atomic masses of the naturally occurring isotopes of an element is the:
Atomic Number
Atomic Mass
Number of Protons
Number of Electrons
Which of the following substances CANNOT be broken down by chemical means?
NaCl
H2O
Argon
Salt Water
The elements on the Periodic Table of Elements are arranged in order of increasing:
electrons
molar mass
atomic mass
atomic number
The most probable location of an electron is known as an:
nucleus
empty space
orbital
positively dense nucleus
Which sample of matter cannot decompose (be broken down) by a chemical change?
helium
water
carbon dioxide
molecule
As electrons move from a higher state of energy to a lower state of energy, energy or a photon is:
released
absorbed
Which two elements are present in this mixture?
hydrogen
Lithium
Helium
Sodium
Rubidium has two common isotopes, 85 Rb and 87 Rb. If the abundance of 85 Rb is 72.2% and the abundance of 87 Rb is 27.8%, what is the average atomic mass of rubidium?
613.7 amu
85.556 amu
84.468 amu
87.556 amu
The picture above shows several different compound models. What is true of compounds?
Compounds are made of only one chemical element.
Compounds are made of two or more different chemical elements.
Compounds always contain at least hydrogen.
Compounds must have at least three atoms that are chemically bonded.
Which is an example of a compound
NO
Fe
Mg
C
What is this?
A compound
A mixture
An atom
An element
Which of the following is NOT a mixture?
milk
air
vegetable salad
carbon
Magnesium
Gold
Identify the substance in box D.
element
compound
mixture
An element is?
Chemically combined
Pure substances that can be broken down
Pure substances that cannot be broken down into simpler substances
One or more elements chemically combined.
Matter is classified as a
substance, only
substance or as a mixture of substances
homogeneous mixture, only
homogenous mixture, only
What is the ground state electron configuration of Br?
2-8-18-7
2-8-18-8
2-3
2-8-17-8
Compute the average atomic mass for this element.
An element exists as the three isotopes shown. What is the average atomic mass?
20.74 amu
22.56 amu
18.39 amu
24.31
