Chemistry Review Grade 9 Science

Neutrons are subatomic particles that have a neutral charge, meaning they do not have a positive or negative charge. Protons have a positive charge, electrons have a negative charge, and madetron and maron are not known subatomic particles. Therefore, the correct answer is neutron.

A proton is a subatomic particle that carries a positive charge. It is found in the nucleus of an atom along with neutrons. Electrons, on the other hand, carry a negative charge and orbit around the nucleus. Therefore, the correct answer is proton.

The electron is a subatomic particle that carries a negative charge. It is one of the fundamental particles that make up atoms. Electrons are found in the electron cloud surrounding the nucleus of an atom and are responsible for the chemical behavior of elements. They play a crucial role in various phenomena such as electricity, magnetism, and chemical reactions.

An ion is a charged atom because it has gained or lost one or more electrons, resulting in an imbalance between the number of protons and electrons. This imbalance creates a positive or negative charge, making the atom an ion.

An object with a greater density than the liquid it is placed in will sink because density is a measure of how much mass is contained in a given volume. If the object has a greater density than the liquid, it means that it has more mass packed into a smaller volume compared to the liquid. This causes the object to be heavier than the liquid and therefore it sinks.

As you move down a column in the periodic table, the number of shells increases. Each row in the periodic table represents a new energy level or shell. As you move from the top to the bottom of a column, the electrons occupy higher energy levels and therefore more shells. This is because the atomic radius increases down a group, allowing for more space for additional electron shells. Therefore, the number of shells increases as you go down a column in the periodic table.

Atoms form ions in order to have a full and stable outer shell. A full outer shell is achieved by either gaining or losing electrons. By forming ions, atoms can either gain or lose electrons to achieve a stable electron configuration, similar to that of a noble gas. This stability is important as it allows atoms to become more chemically stable and less reactive, making them more likely to form attractions with other ions and create compounds.

The atomic mass of an atom is determined by the sum of its protons and neutrons. Protons carry a positive charge and are located in the nucleus of an atom, while neutrons have no charge and are also found in the nucleus. Electrons, on the other hand, have a negative charge and orbit around the nucleus. Since the question asks for the correct answer, it is clear that the atomic mass is equal to the sum of protons and neutrons, as electrons do not contribute significantly to the overall mass of an atom.

The electron has the smallest mass compared to the other subatomic particles listed. Protons and neutrons have approximately the same mass, which is much larger than that of an electron. Emitron and stefatron are not recognized subatomic particles, so they can be ruled out as options. Therefore, the electron is the correct answer as it has the smallest mass.

Lithium ions have a positive charge of 1+. This means that they have lost one electron, resulting in a net positive charge. The positive charge is indicated by the "+" symbol.

As you move from left to right in a period, the atomic radius decreases. This is because the number of protons in the nucleus increases, resulting in a stronger attractive force on the electrons. As a result, the electrons are pulled closer to the nucleus, causing the atomic radius to decrease. Additionally, the increase in the number of electrons in the same energy level also contributes to the decrease in atomic radius.

As you move down the halogens group on the periodic table, the reactivity decreases. This is because the atomic size increases down the group, leading to a weaker attraction between the outermost electron and the nucleus. As a result, it becomes easier for the halogens to gain an electron and form a stable negative ion. Therefore, the ability of halogens to undergo chemical reactions and form compounds decreases as you move down the group, indicating a decrease in reactivity.

The atomic number of an element represents the number of protons in the nucleus of an atom. Protons are positively charged particles, and their number determines the element's identity. Neutrons, on the other hand, are neutral particles found in the nucleus, and their number can vary, resulting in different isotopes of an element. Electrons, which are negatively charged particles, orbit the nucleus and their number can also vary, resulting in ions. However, the atomic number specifically refers to the number of protons, making "protons" the correct answer.

Covalent bonds form when atoms share electrons to achieve a stable electron configuration. This is common in molecules like H2O (water).

Oxygen ions have a charge of 2- because oxygen typically has 6 valence electrons and it gains 2 electrons to achieve a stable octet configuration. This results in a net charge of -2.

Noble gases, also known as inert gases, are a group of elements in the periodic table that are characterized by their low reactivity. They have a full outer shell of electrons, making them stable and unreactive under normal conditions. The noble gases include helium, neon, argon, krypton, xenon, and radon. They are used in various applications, such as lighting, welding, and medical imaging, due to their inert properties.

He-3 is an isotope of helium, which means it has the same number of protons as regular helium but a different number of neutrons. The atomic number of helium is 2, which means it has 2 protons. Since He-3 has 1 neutron, the total number of neutrons in He-3 is 1.

The outer shell of an atom is also known as the valence shell, which determines the chemical properties of the element. In the case of a neutral potassium atom, the atomic number is 19, indicating that it has 19 electrons. The electron configuration of potassium is 2-8-8-1, meaning that there is only 1 electron on the outer shell. Therefore, the correct answer is 1.

C-13 is the isotope of carbon with a mass number of 13, which indicates the total number of protons and neutrons in the nucleus. Since the atomic number of carbon is 6, it means that C-13 has 6 protons.

Carbon-14 is an isotope of carbon, meaning it has the same number of protons but a different number of neutrons. The atomic number of carbon is 6, which represents the number of protons in its nucleus. Since the question asks about the number of neutrons in carbon-14, which has an atomic number of 6, we subtract 6 from the atomic mass of carbon-14, which is 14. This gives us 8, indicating that carbon-14 has 8 neutrons.