The smallest unit of an element that retains the chemical properties of that element.
The tiny building blocks everything is made of. Break matter down far enough, you get atoms.
Showing a random 20 of 50 problems.
Example 1
medium
What kind of microscope can image individual atoms?
Example 2
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An atom has 11 protons, 12 neutrons, and 11 electrons. What is its overall electric charge?
Example 3
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An ion with formula Cl− has 17 protons. How many electrons?
Example 4
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A neutral lithium atom has 3 protons and 4 neutrons. State its number of electrons and its overall charge.
Example 5
easy
Electrons orbit the nucleus in a region called the ____ cloud.
Example 6
easy
Which subatomic particle has the smallest mass?
Example 7
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A neutral atom has 17 protons. How many electrons does it have, and what element is it?
Example 8
challenge
An atom of element X has 26 protons and 30 neutrons. A second atom has 26 protons and 28 neutrons. Give the element, and the difference in their mass numbers.
Example 9
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Why is the mass of an atom essentially the mass of its nucleus?
Example 10
hard
An ion has charge +3 and contains 23 electrons. What is the atomic number of this element?
Example 11
easy
A single gold (Au) particle that still behaves chemically like gold is called a what?
Example 12
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Two atoms both have 6 protons but one has 6 neutrons and the other 7. Are they the same element?
Example 13
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How many electrons does a neutral fluorine atom have?
Example 14
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An atom loses 2 electrons. State the resulting charge and whether the element identity changes.
Example 15
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A neutral atom has mass number 40 and 21 neutrons. Identify the element.
Example 16
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Two atoms have the same atomic number but different mass numbers. What is the term for them?
Example 17
easy
What is the charge of a proton?
Example 18
challenge
A neutral atom has 19 electrons. After a reaction it has a +1 charge. How many protons and how many electrons does it now have, and what element is it?
Example 19
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A neutral atom has 14 protons. How many electrons does it have, and what element is it?
Example 20
easy
If an atom has 8 protons, 8 neutrons, and 8 electrons, what element is it and what is its overall charge?