Atoms 101
Elements, Compounds and Molecules?... Oh my!
Formula Decoded
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Model for the Gram
100
Which subatomic particle has a negative charge?
electrons
100
Which term describes a substance made up of two or more of the same type of atom?
A. Compound
B. Element
C. Molecule
D. Mixture
C. molecule
100
What does the subscript number in a chemical formula tell you?
The number of atoms of that element
100
Elements in the same group (column) of the periodic table usually have the same:
A. atomic mass
B. number of protons
C. number of energy levels
D. chemical/physical properties
D. chemical/physical properties
100
Look at the atomic model shown.
The arrow points to a particle in the center of the atom.
Which subatomic particle is the arrow pointing to in this part of the atom?
protons
200
Which two subatomic particles are found in the nucleus of an atom?
Protons and Neutrons
200
Which statement best describes a compound?
A. A substance made of one atom
B. A substance made of two or more different kinds of atoms
C. A substance made of two or more of the same atom
D. A substance that cannot combine with other substances
B. A substance made of two or more different kinds of atoms
200
How many oxygen atoms are in the chemical formula SO₄?
4 oxygen
200
Why are sodium (Na) and potassium (K) placed in the same group on the periodic table?
A. They are both gases
B. They have the same atomic number
C. They have similar properties
D. They are in the same period
C. They have similar properties
200
In an atomic diagram, which particle is usually shown moving around the nucleus?
electrons
300
On the periodic table, which number tells you how many protons an element has?
the atomic number
300
Which option correctly classifies H₂ and H₂O?
A. H₂ is an element; H₂O is an element
B. H₂ is a compound; H₂O is a compound
C. H₂ is an atom; H₂O is a molecule
D. H₂ is a molecule; H₂O is a compound
D. H₂ is a molecule; H₂O is a compound
300
Use the chemical formula CH₄ to answer the following:
How many carbon atoms are present?
How many hydrogen atoms are present?
Carbon: 1
Hydrogen: 4
300
Which element would have properties most similar to fluorine (F)?
A. Bromine
B. Neon
C. Oxygen
D. Sodium
A. Bromine
300
A model of an atom shows:
15 protons in the nucleus
15 electrons outside the nucleus
16 neutrons
What element does this model represent?
Phosphorus
400
A neutral atom has 15 protons in its nucleus.
How many electrons does this atom have?
15 electrons
400
Classify each substance as an element, compound, or molecule.
A. Na
B. H₂O
C. O₂
Na → Element
H₂O → Compound
O₂ → Molecule
400
A compound contains:
2 carbon atoms
6 hydrogen atoms
1 oxygen atom
Which chemical formula matches this information?
A. C₂H₄O
B. CH₆O
C. C₂H₆O
D. C₆H₂O
C. C₂H₆O
400
Carbon (C) and Oxygen (O) are both nonmetals found in Period 2, but they are located in different groups (columns) on the periodic table.
Which statement is most accurate?
A. They will have the same chemical properties
B. They are in the same group
C. They have different chemical/physical properties
D. They have the same atomic number
C. They have different chemical/physical properties
400
The image shows the modern model of the atom. Which of the following statements best describes this model?
A. The atom has a nucleus made up of positively charged protons and neutral neutrons, and negatively charged electrons move around the nucleus in a cloud.
B. The atom has a nucleus made up of negatively charged protons and neutral neutrons, and positively charged electrons move in fixed circular orbits around the nucleus.
C.The atom has a nucleus made up of negatively charged protons and neutral neutrons, and positively charged electrons move around the nucleus in a cloud.
D. The atom has a nucleus made up of positively charged protons and negatively charged neutrons, and neutral electrons move in fixed circular orbits around the nucleus.
A. The atom has a nucleus made up of positively charged protons and neutral neutrons, and negatively charged electrons move around the nucleus in a cloud.
500
A periodic table entry for an element shows the following information:
Atomic number: 12
Atomic mass: 24.305
Using this information:
How many protons does the atom have?
How many neutrons does the atom have?
How many electrons does the atom have?
Identify the element.
12 protons
12 electrons
12 neutrons
Magnesium
500
A student makes the following claim:
“O₂ and H₂O should both be classified as compounds because they contain more than one atom.”
Do you agree or disagree with the student’s claim?Use evidence from the chemical formulas to support your answer.
Disagree
O₂ is a molecule of an element
Contains only one type of atom
H₂O is a compound
Contains two different elements (hydrogen and oxygen)
Compounds must contain more than one type of atom, not just more than one atom
500
A compound has the chemical formula Fe₂O₃.
List the elements present in the compound.
Identify the number of atoms of each element.
Elements: iron (Fe) and oxygen (O)
Iron: 2 atoms
Oxygen: 3 atoms
500
Four elements are shown below:
A: Sodium (Na)
B: Lithium (Li)
C: Potassium (K)
D: Calcium (Ca)
Which three elements are most likely to have similar chemical properties?
Sodium, Lithium and Potassium
500
Periodic Table shows the locations of five different elements. Which of the letters represents the three elements with the most valence electrons?
Letters B, D, and E