Chemistry Definitions

Question 1

Chemistry

Answer 1

The study of matter and it’s changes

Question 2

Pure Substance

Answer 2

Substance composed of one element of compound

Question 3

Mixture

Answer 3

Substances containing more than one substance

Question 4

State of Matter

Answer 4

The classification of matter as a solid, liquid, or gas

Question 5

Physical Change

Answer 5

Changes that do not alter the identity of the substance

Question 6

Chemical Changes

Answer 6

Changes that produce new substance/ Chemical reactions

Question 7

Chemical Properties

Answer 7

Properties of a substance that cannot be measured w/o changing the identity of a substance

Question 8

Physical Properties

Answer 8

The properties of a substance that CAN measured w/o changing the identity of a substance

Question 9

Kinetic Energy

Answer 9

The energy of motion; (The faster, the greater the energy)

Question 10

Potential Energy

Answer 10

Energy that is stored

Question 11

Exothermic

Answer 11

Physical or chemical change that RELEASES heat energy

Question 12

Endothermic

Answer 12

Physical or chemical change that ABSORBS energy

Question 13

Hypothesis

Answer 13

A tentative explination that has not been tested

Question 14

Experimentation

Answer 14

Test ideas with experiments

Question 15

Theory

Answer 15

An idea that has been tested and refined, or is a paradigm for discribing a particular topic but not Scientific Law

Question 16

What is a Scientific Notation

Answer 16

A way to show very large and very small numbers in a concise formate. Scientific notation expresses numbers as the product of 2 values called coefficient and the multiplyer.

Question 17

Dalton’s Atomic Theory

Answer 17

John Dalton proposed that all matter is composed of indivisible atoms, atoms of the same element are identical, and chemical reactions involve the rearrangement of atoms.

Question 18

Thomson Discovers the Electron

Answer 18

J.J. Thomson discovered the electron in 1897 using a cathode ray tube, proving that atoms contain smaller negatively charged particles.

Question 19

Plum Pudding Model

Answer 19

Electrons that are embedded in a positively charged sphere, like raisins in a pudding.
Electrons that are embedded in a positively charged sphere, like raisins in a pudding.

Question 20

Bohr’s student, Rutherford Proposes the Nucleus Idea as what?

Answer 20

Ernest Rutherford’s gold foil experiment in 1911 said that:

Atoms have a dense, positively charged nucleus surrounded by mostly empty space.

Question 21

Volta’s Electrochemical Cell

Answer 21

Alessandro Volta created the first electrochemical cell (battery) in 1800, proving that electricity could be generated through chemical reactions.

Question 22

Mendeleev’s Periodic Table

Answer 22

Dmitri Mendeleev organized elements into the periodic table in 1869 based on atomic mass and chemical properties, predicting undiscovered elements.

Question 23

What is the Heisenberg uncertainty principle? How does this principle affect our description of electrons?

Answer 23

This principle deals with the mass, velocity, and location of subatomic particles. A central idea of this
principle is that it is impossible to know the exact velocity and location of a particle.

Question 24

What is the Bohr model?

Answer 24

An atom that depicts electrons as orbiting the nucleus in specific, defined energy levels (or shells), similar to how planets orbit the sun

Question 25

Quantum Model

Answer 25

The modern description of electronic behavior that treats electrons as particles and as waves

Question 26

Atoms

Answer 26

The fundamental units of matter

Question 27

Composition

Answer 27

The components that make up a material

Question 28

Structure

Answer 28

The arrangement of simple units within a substance. In chemistry, structure refers to both the composition and arrangement of simple units within a substance

Question 29

Molecules

Answer 29

Groups of atoms that are held tightly together

Question 30

Homogeneous Mixtures

Answer 30

Mixtures in which the components are evenly blended throughout.

Question 31

Heterogeneous Mixtures

Answer 31

Mixtures in which the components are not evenly blended throughout

Question 32

Melting

Answer 32

A Transition from the solid phase to the liquid phase

Question 33

Vaporization

Answer 33

A transistion from the liquid phase to the gas phase

Question 34

Condensation

Answer 34

A transistion from the gas phase to the liquid phase

Question 35

Freezing

Answer 35

A transistion from the liquid phase to the solid phase

Question 36

Chemical Changes

Answer 36

Changes that produce new substances; also called chemical reactions

Question 37

Energy

Answer 37

The ability to do work

Question 38

Scientific Law

Answer 38

A statement that describes observations that are true in widely varying circumstances. They only observe that something occurs

Question 39

Stoichiometry

Answer 39

Using the amount of one material to predict the amount of another, based on the balanced equation.

Question 40

Mass Spectrometry

Answer 40

A technique used to measure the mass of molecules

Question 41

Elemental Analysis

Answer 41

A technique used to measure percent composition uses combustion reactions to form simpler products (CO(2), H(2)O).

Question 42

The Mole Concept

Answer 42

1 atomic mass unit (u) = 1.66 × 10−24 g

Question 43

Avogadro’s Number: Is 1 Mole of what? (Hint: Ekkos Birthday)

Answer 43

6.02 × 10^23

Question 44

How would a Chemists decribe FORMULA MASS?

Answer 44

Chemists calculate the formula mass to know how heavy a single molecule or formula unit of a compound is. It’s expressed in grams per mole (g/mol) or atomic mass units (amu).

Question 45

How would a Chemists decribe PERCENT COMPOSITION?

Answer 45

Percent composition tells chemists what percentage by mass each element contributes to the compound.

Question 46

What’s the Difference Between Heat and Temperature?

Answer 46

Heat is energy in transit due to a difference in temperature. Temperature is a measure of the average kinetic energy of the particles. Example: A hot tub has more heat than a boiling cup of water—even if the water is hotter—because the tub has way more mass and particles.