Midterm Chemisty Flashcards
What is a mixture vs a pure substance?
Mixture: Combination of substances (not chemically bonded).
Pure Substance: Single type of matter (element or compound).
What are physical vs chemical properties?
Physical: Observed without changing identity (color, density).
Chemical: Observed when a substance changes its composition (flammability, reactivity).
What are physical vs chemical changes?
Physical: Changes form, not identity (melting, cutting).
Chemical: Creates new substance (burning, rusting); indicated by color change, gas formation, or temperature change.
What are the phases of matter?
Solid: Fixed shape, particles tightly packed.
Liquid: Takes the shape of the container, particles slide past each other.
Gas: Expands to fill space, particles move freely
Describe the atomic structure
Protons (+) and neutrons (0) in nucleus.
Electrons (-) orbit nucleus.
Atomic number = number of protons.
How do you write chemical formulas?
Show number of atoms in a compound (e.g., H₂O = 2 hydrogen, 1 oxygen).
What is an atom?
The smallest identifiable unit of an element
What is a nucleus?
A small core containing most of the atom’s mass and all of its positive charge; made up of protons and neutrons
What is a proton?
Positively charged particle inside the nucleus of an atom
What is a neutron?
A nuclear particle that has no charge and nearly the same mass as the proton
What is an electron?
A negatively charged particle that occupies most of the atom’s volume but contributes almost none of its mass
