Chem Midterm Review

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What is a physical change?

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A physical change is a change that affects one or more physical properties of a substance without altering its chemical composition. Examples include freezing, melting, and dissolving.

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What is an isotope?

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An isotope is a variant of a chemical element that has the same number of protons but a different number of neutrons. For example, Carbon-14 has 6 protons and 8 neutrons.

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What is a heterogeneous mixture?

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A heterogeneous mixture is a mixture in which the components are not uniformly distributed and can be easily distinguished. An example is a tuna fish salad sandwich.

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What is an orbital in chemistry?

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An orbital is a region in an atom where there is a high probability of finding electrons. Different types of orbitals include s, p, d, and f orbitals.

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Which orbital can never exist?

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The 3d orbital can never exist as it is not a valid quantum state.

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How many hydrogen atoms are in (NH4)2CO3?

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There are 8 hydrogen atoms in (NH4)2CO3.

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What is the difference between a physical change and a chemical change?

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A physical change alters the form or appearance of a substance without changing its chemical composition, while a chemical change results in the formation of new substances.

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What is the atomic number of an element?

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The atomic number is the number of protons in the nucleus of an atom, which determines the element's identity.

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What is a chemical formula?

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A chemical formula is a way of expressing information about the proportions of atoms that constitute a particular chemical compound.

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What is the law of conservation of mass?

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The law of conservation of mass states that mass is neither created nor destroyed in a chemical reaction.