8th Grade Chemistry - Quiz 2: Endo/Exo, P Table, + Diagrams

This is the study guide/flashcards for a 8th grade level chemistry test.

What is an Atom?

The smallest unit of matter, made up of protons, neutrons, and electrons.

What is an Element?

A pure substance made of only one kind of atom; is found on the periodic table.

What are Molecules?

Two or more atoms chemically bonded together, which can be the same or different elements.

What are Beakers?

Used to hold, mix, and heat liquids; not great for precise measurements.

What are Flasks?

Used to swirl and mix liquids without spilling; good for heating.

What are Graduated Cylinders?

Used to measure the volume of liquids accurately (in mL).

What are Pipettes?

Used to transfer small amounts of liquids.

What is a Balance?

Used to measure the mass of solids, usually in grams.

What is a Hot Plate?

Used to heat substances.

What are Test Tubes?

Hold small amounts of substances for reactions and experiments.

How do you measure solids?

Measured using balances in grams (g).

How do you measure liquids?

Measured using graduated cylinders or pipettes in milliliters (mL).

How do you measure temperature in science class?

Measured in Celsius using a thermometer.

What is an Endothermic Reaction?

A reaction that absorbs energy or heat from surroundings, causing temperature to drop.

What is an Exothermic Reaction?

A reaction that releases energy or heat into surroundings, causing temperature to rise.

Who was Dmitri Mendeleev?

Created the modern Periodic Table of elements in 1869 by arranging them by atomic mass.

Groups in Periodic Table

Columns where elements have similar chemical properties due to the same number of valence electrons.

Periods in Periodic Table

Rows where elements have the same number of electron shells.

Protons

Subatomic particles with a positive charge that determine the element's identity.

Neutrons

Subatomic particles with no charge, important for stabilizing the atom.

Electrons

Subatomic particles with a negative charge that orbit the nucleus.

How do you find the PEN?

Protons equal atomic number; electrons are also the atomic number; neutrons equal atomic mass minus the number of protons.

What is a Bohr Diagram?

A diagram showing the nucleus with protons and neutrons, and electrons in shells around it.

What is a Lewis Dot Diagram?

A diagram representing an element symbol and dots around it representing the number of valence electrons.

What are the 4 families of the periodic table?

The four families are Alkali Metals, Alkaline Earth Metals, Halogens, Transition Metals, and Noble Gases.

Where are the four families located on the periodic table?

Alkali Metals are in Group 1, Alkaline Earth Metals in Group 2, Halogens in Group 17, and Noble Gases in Group 18. Groups 3-12 are transition metals. Groups 13-16 aren’t important in this part of chemistry.

How can you use the group number that the element is in to find the number of valence electrons [rule]?

Look at the one place of the group number. For groups 1 and 2, the number of valence electrons corresponds directly to the group number. For groups 13-18, subtract 10 from the group number to find the number of valence electrons.

Who created the modern Periodic Table of elements?

Dmitri Mendeleev created the modern Periodic Table of elements in 1869.

Why was Mendeleev's theory accepted?

His theory was accepted because he arranged elements by atomic mass and predicted properties of undiscovered elements.

How is the periodic table organized?

The periodic table is organized by increasing atomic number (number of protons + electrons) and arranged in groups (columns) and periods (rows).

How can you use trends in the periodic table to predict certain properties of elements?

Trends like valence electrons and reactivity help predict how elements behave with others.

What are groups and periods?

Groups are vertical columns where elements have similar properties. Periods are horizontal rows where elements have the same number of electron shells.

What are metals, nonmetals, and metalloids?

Metals are good conductors of electricity and are usually solid, nonmetals can be gases or solids and are poor conductors, and metalloids have properties of both.

What are valence electrons?

Valence electrons are the electrons on the outer shell (orbital) of an atom.

What are trends in the periodic table related to valence electrons and metallic character?

As you move down a group in the periodic table, the number of valence electrons remains constant while the metallic character increases. Or, as you move from left to right across a period, the metallic character decreases and the number of valence electrons increases.