Physical vs. Chemical
Is tearing a piece of paper into small pieces a physical change or a chemical change?
Physical change.
Is a sample of pure gold (Au) considered an element, a compound, or a mixture?
Element
The vertical columns on the periodic table are called groups or families. What are the horizontal rows called?
Periods.
What is the fundamental building block of matter that retains the properties of an element?
Atom
What is the definition of matter?
Anything that has mass and takes up space (has volume).
Is iron rusting when exposed to oxygen and water a physical property or a chemical property?
Chemical property (reactivity with oxygen).
What type of mixture has a uniform composition throughout, like saltwater or air?
Homogeneous mixture (or a solution).
Most of the elements on the periodic table belong to which major classification: metals, nonmetals, or metalloids?
Metals
In a chemical reaction, the starting substances are called reactants. What are the substances formed by the reaction called?
Products
Which state of matter has a definite volume but no definite shape, taking the shape of its container?
Liquid
Name at least two common signs/evidence that a chemical reaction has taken place.
(Any two of): Color change, formation of a gas (bubbles), formation of a precipitate (solid), release/absorption of heat or light.
A substance made of two or more different elements chemically bonded together in a fixed ratio is called a what?
Compound (e.g., H_2O, NaCl).
Elements located along the zigzag line (staircase) on the periodic table that share properties of both metals and nonmetals are called what?
Metalloids (or semimetals).
What is the chemical symbol for Sodium?
Na
Describe the shape and volume of a gas.
A gas has no definite shape and no definite volume (it expands to fill its container).
Is density a physical property or a chemical property?
Physical property (specifically an intensive physical property).
A bowl of Italian salad dressing with oil, vinegar, and herbs is an example of what specific type of mixture?
Heterogeneous mixture.
Name three physical properties typical of metals.
Good conductors of heat/electricity, malleable, ductile, shiny/lustrous.
What is the difference between an extensive physical property and an intensive physical property?
Extensive properties depend on the amount of matter present (e.g., mass, volume); intensive properties do NOT depend on the amount of matter (e.g., density, boiling point).
How do the particles in a solid move compared to the particles in a liquid or gas?
Particles in a solid vibrate in place; in liquids and gases, they slide past each other or move freely.
Why is burning wood considered a chemical change, while melting ice is only a physical change?
Burning wood creates entirely new substances (CO_2, ash, water vapor), while melting ice is just a change of state (water molecules remain H_2O).
What is the key difference between how a mixture can be separated versus how a compound can be separated?
Mixtures can be separated by physical means (filtration, evaporation); compounds can only be separated by chemical means (chemical reactions).
Why do elements in the same group (family) on the periodic table exhibit similar chemical properties?
They have the same number of valence electrons.
State the Law of Conservation of Mass in your own words.
Mass is neither created nor destroyed during an ordinary chemical or physical reaction (mass of reactants = mass of products).
High-temperature state of matter in which atoms lose most of their electrons, creating a plasma-like charged gas, is found naturally in stars. What is this state called?
Plasma