Cobalt has a mass number of 59 and an atomic number
of 27. A student wants to create a model of a cobalt
atom. Which statement about the model is correct?
(1 point)
The model should show 32 protons and
59 neutrons.
The model should show 59 protons and
27 neutrons.
The model should show 27 protons and
32 neutrons.
The model should show 27 protons and
27 neutrons.
The correct statement about the model is: The model should show 27 protons and 32 neutrons.
The model should show 27 protons and 32 neutrons.
To determine which statement about the model of a cobalt atom is correct, we need to understand the relationship between the atomic number and mass number.
The atomic number of an atom represents the number of protons in its nucleus. In this case, cobalt has an atomic number of 27, so it has 27 protons.
The mass number of an atom represents the total number of protons and neutrons in its nucleus. In this case, cobalt has a mass number of 59.
Since the atomic number (protons) represents 27 and the mass number (protons + neutrons) represents 59, we can subtract the atomic number from the mass number to determine the number of neutrons.
Number of neutrons = mass number - atomic number
Number of neutrons in cobalt = 59 - 27 = 32
Therefore, the correct statement about the model of a cobalt atom is:
The model should show 27 protons and 32 neutrons.
In a molecule of lithium sulfide, there are two atoms of
lithium and one atom of sulfur. Which statement about
lithium sulfide is correct? (1 point)
The atoms in lithium sulfide are held
together by bonds.
A molecular model of lithium sulfide
would have two spheres.
The chemical formula for lithium sulfide
is LiS . 2
Both lithium and sulfur form positive ions.
The correct statement about lithium sulfide is: Both lithium and sulfur form positive ions.
Which element has the same number of valence
electrons as bromine (Br)?
(1 point)
selenium (Se)
potassium (K)
krypton (Kr)
chlorine (Cl)
The element that has the same number of valence electrons as bromine (Br) is chlorine (Cl).
Why are sodium (Na) and potassium (K) in the same
group on the periodic table? (1 point)
They have similar atomic weights.
They are both hard and brittle.
They are both colorless.
They have similar reactivity
Sodium (Na) and potassium (K) are in the same group on the periodic table because they have similar reactivity. The elements in the same group of the periodic table have similar chemical properties and tend to react in similar ways. Sodium and potassium both belong to Group 1 or the alkali metals, which are highly reactive and have similar properties such as low melting points and the ability to easily lose their outermost electron to form a positive ion.
Which of the following is considered acidic? (1 point)
Lime Water
Vinegar
Soap
Ammonia