Mcat Chem 1

An atom is the basic unit of matter and is composed of a Nucleus made up of Protons and Neutrons, surrounded by Electrons. The incorrect answers provided do not accurately define what an atom is.

A nucleus is the central part of an atom that contains protons and neutrons, held together by the strong nuclear force. It is not a type of cell, a unit of measurement, or a negatively charged particle.

An electron is a negatively charged particle that orbits the nucleus of an atom, not found within the nucleus itself. It is not positively charged nor a unit of energy measurement in physics.

An element is a pure substance composed of only one type of atom and cannot be further broken down into simpler substances by chemical means.

The labels for the elements in the periodic table are called atomic symbols, which are one or two letter abbreviations for each element.

Isotopes are defined by having the same number of protons, but different number of neutrons which leads to variations in mass.

Atomic weight is a weighted average considering isotopes, not the total number of particles in the nucleus, not the same as atomic number, and not just the mass of a single atom.

The correct way to calculate moles is by using the formula: Moles = Mass / Molar Mass

Avogadro's number is a constant that represents the number of particles (atoms, molecules, ions, etc.) in one mole of a substance. It is approximately 6.022 x 10^23.

The Periodic Table is organized into periods, which are horizontal rows, and groups, which are vertical columns. The families of elements include Metals (Alkali, Alkaline Earth, Transitional), Metalloids (thin diagonally flowing group), and Non-metals (Covalent and pi bonding, Halogens, Nobel Gases.

Metals generally exhibit positive charge in bonds, form ionic bonds with oxygen (excluding BeO), are ductile, malleable, conductive of heat and electricity, and exhibit a lustrous appearance. This set of characteristics distinguishes metals from other elements.

This question tests knowledge of the characteristics of different types of metals. Alkali metals have lower melting points, are highly reactive, softer and less dense, and form +1 cations. Alkaline metals, on the other hand, have higher melting points, are less reactive, harder and more dense, and form +2 cations. Transition metals have varying melting points, are moderately reactive, have moderate hardness and density, and form +2 cations. Noble metals have very high melting points, are non-reactive, very hard and dense, and do not form cations. Heavy metals have high melting points, are reactive, soft and slightly less dense, and form -1 cations.

Metalloids exhibit properties that are intermediate between metals and nonmetals, such as having some metallic and some nonmetallic properties.

Non-metals generally form covalent bonds, have high electronegativity, and tend to gain electrons in chemical reactions. They are poor conductors of electricity and heat and are usually not dense.

Cations become smaller when they lose an outer shell because they are more positively charged and the electron-electron repulsion decreases. This causes the remaining electrons to be pulled closer to the nucleus, resulting in a smaller size.

Shielding in the context of ion formation refers to the phenomenon where the outermost electron shields the inner electrons from the increased attractive force of the protons after the removal of an electron. This concept helps explain the Effective Nuclear Charge felt by the remaining electrons.

The periodic trends involve specific properties such as ionization energy, electronegativity, electron affinity, radius, and metallic character. Understanding how these properties change across periods and groups in the periodic table is crucial in predicting chemical behavior.

It is important to have a solid understanding of the SI units and prefixes to easily convert between different units and perform calculations in science and engineering.

Covalent bonds involve the sharing of electrons between atoms, rather than transferring, losing, or gaining them.

Bond length refers to the specific distance between two bonded atoms where the attractive and repulsive energy levels are optimized for stability.

Bond dissociation energy is the amount of energy required to completely break the bond between two atoms, not the energy released when forming a bond or the energy needed to form or break a bond.

A compound is formed by the chemical combination of two or more different elements in a fixed ratio, leading to the creation of a unique substance with distinct properties.

The empirical formula represents the simplest whole-number ratio of the elements in a compound, while the molecular formula provides the exact number of each atom in a molecule. The chemical formula typically refers to the combination of symbols representing the elements in a compound. The structural formula shows the arrangement of atoms within the molecules.

The molecular formula of a compound provides information on the composition of elements present in the compound in terms of their exact numbers.

To find the percent mass of an element in a compound using the empirical formula, you need to divide the molecular weight of the element by the molecular weight of the empirical formula and then multiply by 100.

To find the empirical formula from percent mass, you need to calculate the ratio of each element by dividing the percentage of the element by its atomic weight. This ratio gives you the subscript for each element in the empirical formula.

The naming rules provided cover various scenarios for naming compounds based on the type of elements and the presence of oxygen or nitrogen. These rules are essential in correctly identifying and naming different types of chemical compounds.

Physical reactions refer to changes in state such as melting, freezing, condensation, and evaporation without altering the chemical composition of substances.

A chemical reaction specifically involves the change in chemical structure resulting in a new compound being formed.