Key Terms Test Chemical Interactions Chapter 1 Section 1

Matter is anything that has mass and occupies space. It refers to the physical substances that make up the universe, including both living and non-living things. Matter can exist in various forms such as solid, liquid, or gas. This definition encompasses all objects and substances that we can perceive and interact with in our everyday lives.

An element is a substance that cannot be broken down into any other substances by chemical or physical means. This means that elements are the fundamental building blocks of matter and cannot be further simplified or decomposed into simpler substances. Each element is characterized by its unique atomic number, which represents the number of protons in the nucleus of its atoms. Examples of elements include hydrogen, oxygen, carbon, and gold.

A compound is a substance that is formed by the chemical combination of two or more elements in a specific ratio or proportion. In other words, it is a substance that has a fixed composition and can be broken down into simpler substances through chemical reactions. Compounds are different from mixtures, as mixtures can be separated into their individual components through physical means. Compounds have unique properties that are different from the properties of their constituent elements, making them distinct substances.

A mixture is a combination of two or more substances that are physically mixed together but do not undergo a chemical reaction. In a mixture, the substances retain their individual properties and can be separated by physical means, such as filtration or distillation. This is different from a chemical compound, where the elements are chemically combined and cannot be easily separated.

An atom is the smallest particle of an element that retains the chemical properties of that element. It consists of a nucleus, which contains protons and neutrons, and electrons that orbit around the nucleus. Atoms combine to form molecules and compounds.

A scientific theory is a well-tested idea that explains and connects a wide range of observations. It is not a particle of an element, a mixture of substances, or a substance made of elements chemically combined. A scientific theory is based on extensive research and experimentation and is supported by evidence. It provides a framework for understanding and predicting natural phenomena.

The correct answer is the central core of the atom, containing protons and usually neutrons. This is because the nucleus is the densest part of an atom and is composed of positively charged protons and neutral neutrons. It is responsible for the mass of the atom and determines its identity. The electrons, which are negatively charged particles, orbit around the nucleus.

Electrons are negatively charged particles that orbit around the nucleus of an atom. They are the smallest subatomic particles and have a negligible mass compared to protons and neutrons. Electrons play a crucial role in chemical reactions and the formation of chemical bonds.

The answer correctly defines an energy level as a region within an atom where electrons with the same energy are likely to be found. This definition aligns with the concept of energy levels in atomic structure, where electrons occupy specific energy levels or orbitals around the nucleus. Each energy level can hold a specific number of electrons, and electrons within the same energy level have similar energy.

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Neutrons are small, uncharged particles that are found in the nucleus of an atom. This means that they do not have a positive or negative charge like protons or electrons. Neutrons play a crucial role in determining the stability and mass of an atom. They help to hold the nucleus together by balancing the repulsive forces between the positively charged protons. The number of neutrons in an atom can vary, resulting in different isotopes of the same element.