Chemistry Quiz - Level 2

Ions are created by gaining or losing electrons. When an atom gains or loses electrons, it becomes electrically charged and forms an ion. If an atom gains electrons, it becomes negatively charged and forms a negative ion (anion). If an atom loses electrons, it becomes positively charged and forms a positive ion (cation). Therefore, the correct answer is electrons.

Bonding occurs between atoms to make them more stable by filling their outer electron shells. When atoms bond, they share, gain, or lose electrons to achieve a full outer shell, which is the most stable electron configuration. This stability is achieved by reducing the energy of the system, making bonding a favorable process. Therefore, the statement that bonding helps make atoms more stable is true.

Ions are atoms or groups of atoms that have a charge. This means that they have gained or lost electrons, resulting in a positive or negative charge. Therefore, the statement that atoms or groups of atoms with a charge are called ions is true.

Avogadro's Number is a fundamental constant in chemistry and physics that represents the number of atoms or molecules in one mole of a substance. It is approximately equal to 6.02 x 10^23 particles per mole. This value is derived from Avogadro's constant, which is the number of atoms in exactly 12 grams of carbon-12. Therefore, the correct answer is 6.02 x 10^23.

The property of metals that relates to the given statement is electrical conductivity. In metallic bonds, the outer electrons of metal atoms are delocalized, meaning they are not bound to any specific atom and are free to move throughout the material. This allows metals to conduct electricity as the free electrons can carry electric current.

Atoms are neutral because they have the same number of protons and electrons. Protons have a positive charge, while electrons have a negative charge. Since the charges of protons and electrons are equal in magnitude, the atom as a whole has no net charge and is therefore neutral.

Fluorine, chlorine, and bromine are all halogens, which belong to Group 17 of the periodic table. Halogens have a tendency to gain one electron to achieve a stable electron configuration, resulting in the formation of an ion with a charge of -1. Therefore, the correct answer is -1.

Non-metal atoms join together with a covalent bond. In a covalent bond, non-metal atoms share electrons in order to achieve a stable electron configuration. This type of bond occurs between two non-metal atoms or between a non-metal and a hydrogen atom. Covalent bonds are typically strong and result in the formation of molecules.

Ionic bonds occur between metal and non-metal atoms. This is because ionic bonds involve the transfer of electrons from the metal atom to the non-metal atom, resulting in the formation of ions with opposite charges. The attraction between these ions creates a strong bond.

The correct answer is MgCl2. This is because the formula for Magnesium Chloride consists of one magnesium ion (Mg2+) and two chloride ions (Cl-), resulting in the formula MgCl2.

Covalent molecular substances have weak intermolecular bonds, which means that the molecules are held together by relatively weak forces. These weak intermolecular bonds result in low melting and boiling points for covalent molecular substances. When heat is applied, the weak forces between the molecules are easily overcome, causing the substance to melt or boil at relatively low temperatures. Therefore, the correct answer is low melting and boiling points.

To calculate the number of moles in a substance, we use the formula: moles = mass / molar mass. The molar mass of oxygen is approximately 16 g/mol. Therefore, we can calculate the number of moles by dividing the given mass of 36.8 grams by the molar mass of oxygen. The result is 2.3 moles.

Avogadro's Number is based on the element Carbon. This number represents the number of atoms or molecules in one mole of a substance. It is defined as 6.022 x 10^23 and is used in various calculations in chemistry, such as determining the number of atoms in a sample or calculating molar mass. Carbon is chosen as the basis for Avogadro's Number because it is a common element found in many compounds and has a relatively stable atomic mass.

The group number on the periodic table helps with predicting the charge of an ion that a particular atom will create. This is because elements in the same group have similar chemical properties and tend to form ions with the same charge. For example, elements in Group 1 (such as sodium and potassium) tend to form ions with a +1 charge, while elements in Group 2 (such as magnesium and calcium) tend to form ions with a +2 charge. Therefore, knowing the group number of an atom can provide information about the charge of the ion it will form.

The molecular mass of NaCl is 58.44. This is the sum of the atomic masses of sodium (Na) and chlorine (Cl) in one molecule of NaCl. Sodium has an atomic mass of 22.99 and chlorine has an atomic mass of 35.45. Adding these two values together gives us a total of 58.44.

The molar mass of iron (Fe) is 55.845 g/mol. To calculate the mass of 3.6 moles of iron, we can multiply the molar mass by the number of moles: 55.845 g/mol * 3.6 mol = 201.06 g.