Chemistry Basics Quiz

Chemistry Basics

• Chemistry is defined as the study of matter and the changes it undergoes.
• Matter is anything that occupies space and has mass.

Types of Observations

• Qualitative observations involve general descriptions of a system.
• Quantitative observations are numerical data obtained from measurements.

Mixtures and Substances

• Mixtures combine two or more substances while retaining their distinct identities.
• A homogenous mixture has uniform composition throughout, whereas a heterogenous mixture does not.
• Elements cannot be separated into simpler substances via chemical means, while compounds consist of two or more elements combined in fixed proportions.

Properties of Matter

• Physical properties can be measured without altering the substance's identity.
• Chemical properties require a chemical change for observation.

Units of Measurement

• Kelvin (K) is the SI unit for temperature, with absolute zero defined as 0 K or -273.15 degrees Celsius.

Measurement Accuracy and Precision

• Accuracy refers to how close a measurement is to the true value.
• Precision indicates how consistently multiple measurements agree with each other.
• Significant figures are the meaningful digits present in a measured or calculated quantity.

Fundamental Laws

• The law of definite proportions states that samples of the same compound always have their elements in the same mass ratio.
• The law of conservation of mass asserts that matter cannot be created or destroyed.

Atomic Structure

• Atoms are the basic units of elements that can engage in chemical combinations.
• Radiation is the transmission of energy through space in wave form; radioactivity refers to the spontaneous emission of particles or radiation.
• The atomic number defines the number of protons in an atom, while the mass number is the total number of protons and neutrons.

Isotopes and the Periodic Table

• Isotopes are atoms with the same atomic number but different mass numbers.
• The periodic table categorizes elements with similar properties; periods are horizontal rows, and groups (families) are vertical columns.

Groups of Elements

• Alkali metals are found in group 1A, alkaline earth metals in group 2A, halogens in group 7A, and noble gases in group 8A.

Molecules and Ions

• Molecules are formed when atoms lose or gain electrons.
• Ions are charged particles that result from this electron transfer; cations have a positive charge, while anions carry a negative charge.

Chemical Representation

• Chemical formulas express the composition of molecules and ionic compounds using chemical symbols.
• Molecular formulas indicate the exact number of atoms for each element, while empirical formulas show the simplest whole number ratio of atom types.

Mass Concepts

• Atomic mass reflects the mass of an atom in atomic mass units (amu) or grams.
• Molecular mass is the sum of the atomic masses within a molecule and is treated similarly to atomic mass.

Mole Concept

• A mole (mol) represents a quantity of substance containing the same number of particles as there are atoms in 12 grams of carbon-12, serving as a convenient counting method in chemistry.