Chemistry: Matter and Periodic Table

Matter

• Pure substances contain only one type of matter. Elements and compounds are types of pure substances.
• Mixtures contain two or more substances.
• Compounds are formed when two or more different types of atoms bond together.
• Elements are the simplest form of matter, cannot be broken down further and all atoms within an element are identical.

Periodic Table

• Elements are arranged in order of increasing atomic number (number of protons).
• Elements are categorized as metals, nonmetals, and metalloids.
• Metals generally lose electrons to form positive ions (cations).
• Nonmetals generally gain electrons to form negative ions (anions).
• Metalloids exhibit properties of both metals and nonmetals.
• Elements in the same group (column) have similar properties due to similar numbers of valence electrons.
• Elements in the same period (row) have different properties.
• Group 1 elements are alkali metals (highly reactive).
• Group 2 elements are alkaline earth metals (highly reactive).
• Group 17 are Halogens.
• Group 18 are Noble Gases (very unreactive).

Atomic Structure

• Atoms are composed of protons, neutrons, and electrons.
• Protons and neutrons are located in the nucleus.
• Protons have a positive charge.
• Neutrons have no charge.
• Electrons have a negative charge and are found outside the nucleus.
• The number of protons defines the element.
• Atomic number = number of protons.
• Atomic mass = number of protons + neutrons.

Atomic Structure and Location

• Atoms are mostly empty space.
• Electrons are found in specific energy levels or shells around the nucleus.
• Each energy level has a certain capacity for electrons.
• Electrons absorb energy to move to higher energy levels (excited state).
• Electrons emit energy to return to lower energy levels (ground state).
• Valence electrons are those in the outermost energy level.

Calculations

• All nonzero digits are significant figures.
• Zeroes between nonzero digits are significant.
• Zeroes to the right of a decimal point but before a nonzero digit are insignificant.
• Zeroes used for placeholding are not significant.
• When multiplying or dividing, the final answer has the fewest significant figures of any number in the calculation.
• When adding or subtracting, the final answer has the fewest decimal places of any number in the calculation.
• Density = mass/volume
• Percent error = [(measured value - actual value)/actual value] × 100

Explore the fundamentals of matter, including pure substances, mixtures, and the properties of elements and compounds. This quiz also covers the organization of the periodic table, categorization of elements, and their properties based on location within the table.