Chemistry Basics Quiz

Chemistry is considered "central" because it forms the foundation for other science fields, as it deals with the composition, structure, and properties of substances.

Inorganic chemistry focuses on compounds that lack carbon atoms, usually in the study of mineral and geological structures.

Scientific notation is a way to express very large or very small numbers in a compact form. It uses exponents to represent the number of decimal places a number is shifted.

Matter is anything that has mass and takes up space. It's essentially everything you can touch and see.

Liquids have a fixed volume but can take the shape of their container.

Protons are positively charged particles located in the center of an atom, called the nucleus.

A physical change alters the form or appearance of a substance but doesn't change its composition, like ice melting into water.

A homogeneous mixture is a uniform blend of two or more substances, like saltwater, where the components are evenly distributed.

Compounds are substances formed by the chemical combination of two or more elements in a fixed ratio, such as water (H2O) or carbon dioxide (CO2).

A chemical property describes how a substance reacts or changes in the presence of other substances, like flammability.

The Law of Conservation of Mass states that in a closed system, the total mass of the reactants before a chemical reaction equals the total mass of the products after the reaction.

Saltwater is a homogenous mixture because the salt and water are evenly distributed, resulting in a uniform appearance.

A heterogeneous mixture has components that are unevenly distributed, meaning you can see the different parts, like sand and water or oil and water.

The estimated digit in a measurement is the last digit, the one with the least certainty, representing the uncertainty in the measurement.

Significant figures or digits are the meaningful figures in a measurement, showing the precision of the measurement.

Scientific notation provides a concise way to express very small numbers, like 0.0045, by representing the decimal places as an exponent, in this case, 4.5 x 10-3.

Density is a measure of how much mass is packed into a given volume. It is calculated by dividing the mass of a substance by its volume.

When adding or subtracting numbers, round the answer to the same decimal place as the number with the fewest decimal places. In this case, 275 has zero decimal places, 9.3 has one, so the answer rounds to the nearest whole number (284).

Rounding to one significant figure involves keeping only the first non-zero digit and replacing the remaining digits with zeros. In this case, 0.047 rounds up to 0.05.

When adding or subtracting, round the result to the same number of decimal places as the number with the fewest decimal places. In this case, 7.68 m has two decimal places and 5.0 m has one, so we round the answer (12.68 m) to one decimal place (12.7 m).

When multiplying or dividing, round the result to the same number of significant figures as the number with the fewest significant figures. In this case, 2.2 mm has 2 significant figures, 5.00 mm has 3, so we round the answer (11.00 mm2) to 2 significant figures (11 mm2).

The atomic mass is an average weighted value of the masses of all isotopes of an element. It takes into account the abundance of each isotope.

The atomic mass is calculated by taking the weighted average of the masses of all the isotopes an element is known to possess. If the abundance of Argon-39 is less than Argon-40, then its contribution to the average atomic mass is smaller.

The sodium ion (Na+) has 11 protons, 12 neutrons, and 10 electrons. It has lost one electron to become positively charged, which is why it has one fewer electron than protons.

In J.J. Thomson's experiment, the cathode tube produced a beam of rays that were attracted to a positively charged plate. This indicated that these particles must be negatively charged.

Ernest Rutherford conducted the Gold Foil Experiment, where he fired alpha particles at a thin gold foil and observed that some particles deflected at large angles. This led to the discovery of the atomic nucleus.

This atom has 29 protons and 29 neutrons. The number of protons is equal to its atomic number, which is 29 for copper.

The number of neutrons in an atom is calculated by subtracting the atomic number from the mass number (number of protons + number of neutrons).

Carbon-14 has 6 protons, 8 neutrons, and 6 electrons. The number of protons is equal to the atomic number (6), and the number of electrons is equal to the number of protons.

The electron configuration of silicon is 1s2 2s2 2p6 3s2 3p2. This shows the distribution of electrons in different energy levels and orbitals.

This is a correctly drawn orbital diagram for oxygen: [A correctly drawn orbital diagram of oxygen]

Elements found in the d-block are called transition metals. They have at least 21 electrons because they have one or more d orbitals filled.

Isotopes are atoms of the same element that have the same number of protons but a different number of neutrons, making their atomic masses different.

An orbital is a three-dimensional region of space within an atom where there is a high probability of finding an electron.

The electron configuration 1s2 2s3 is not possible because it violates the Aufbau principle. The 2p orbital should be filled before the next energy level.

Chlorine (Cl) has 17 protons. Its atomic number is 17, and the number of protons in an atom is equal to its atomic number.

Iron (Fe) has 30 neutrons. Its atomic number is 26, and its mass number is 56. The number of neutrons is the difference between the mass number and the atomic number.

Electrons determine an atom's chemical behavior because they are the outermost particles and can be shared or transferred during chemical reactions.

Carbon-13 has 7 neutrons. Its atomic number is 6, and its mass number is 13. The number of neutrons is the difference between the mass number and the atomic number.

The second energy level (n=2) in an atom consists of the 2s and 2p orbitals. There is one s orbital and three p orbitals at each energy level.

Ca+2 has 20 protons. It has a +2 charge, meaning it has lost two electrons. The number of protons remains the same.

The 4s sublevel fills before the 3d sublevel because it has a lower energy level. An element with n=5 can hold up to 50 electrons because the fifth energy level has 5 sublevels (s, p, d, f, g).

This is a play on words about positive and negative charges, common in chemistry. Hydrogen, a single proton, is positively charged when it loses its electron.

The correct electron configuration follows the Aufbau principle and Hund's rule, filling orbitals in order of increasing energy.

The oxide ion (O2-) is the smallest ion. It has gained two electrons, reducing its size. Cations are generally smaller than their parent atoms, while anions are generally larger.

The photoelectric effect is a phenomenon where electrons are emitted from a material when light shines upon it. This happens because the energy of the light transfers to electrons, allowing some of them to escape.

The electron configuration 1s22s22p63s23p64s23d104p6 corresponds to Krypton, a noble gas element. It has all its orbitals filled.

The electron configuration given is NOT valid for a neutral atom because it violates the Aufbau principle (filling orbitals in order of increasing energy).

Phosphorus. The orbital diagram depicts the filling of orbitals in phosphorus. It has 5 valence electrons in 3s and 3p orbitals.

The number of protons in an atom is always equal to its atomic number. The atomic number is also used to identify the element.

The number "14" in Carbon-14 represents the mass number of the isotope. The mass number signifies the total number of protons and neutrons in the nucleus of an atom.

The orbital diagram shown for phosphorus is a correct representation of the filling of its orbitals based on Hund's rule, which states that electrons will occupy individual orbitals within a subshell before pairing up in the same orbital.

Metals share some common characteristics, including malleability (can be hammered into thin sheets), electrical conductivity, and luster (shiny appearance).

Rubidium (Rb) has the lowest ionization energy among the listed options because it is an alkali metal, meaning it has a very low ionization energy. It readily loses its outermost electron to form a cation.

Inner-transition metals, sometimes called f-block elements, are found in the two rows that are typically placed beneath the main body of the periodic table. They have f orbitals being filled.

Barium (Ba) is an alkaline earth metal, a group of elements that have a +2 charge when they become ions.

Transition metals are found in the d-block of the periodic table. They are known for their varied oxidation states and color.

Metalloids, sometimes called semiconductors, have properties of both metals and nonmetals. Boron (B) is a metalloid.

Chlorine (Cl) is a nonmetal element found in the p-block of the periodic table. It has a high electronegativity and is very reactive.

Lithium (Li) is in the 2nd period of the periodic table. The period number corresponds to the principal energy level (n) of the outermost electron.

A p-orbital has a dumbbell shape, with two lobes on opposite sides of the nucleus. There are three p-orbitals in each shell (except the first shell).

Aluminum (Al) will not form a +2 cation because its electron configuration makes it more stable to lose three electrons and form a +3 cation. It needs to lose all three electrons to reach a noble gas configuration.