Unit 1 Flashcards
What does special relativity state about time and space?
Time and space are not absolute but are relative to each other.
What is the relationship between the force of attraction between masses and the distance between them?
The force is proportional to the product of the masses and inversely proportional to the square of the distance between them.
How many protons does an atom of hydrogen have?
One proton.
What happens to a reaction when reagent X is added?
The reaction goes faster.
What is the difference between a Law and a Theory?
A Law describes the phenomenon while a Theory explains the phenomenon.
What is a Scientific Theory?
The best available explanation of existing evidence/data/observations.
What are the characteristics of a Scientific Theory?
- Explains how and/or why
- Makes testable predictions
- Is falsifiable
- May change over time as new evidence becomes available.
What distinguishes one element from another?
The types of atoms they contain.
What is the smallest unit of an element?
An atom.
What is the difference between a molecule and a compound?
A molecule contains more than 2 atoms; a compound contains more than 2 types of elements.
Which elements are ordered on the periodic table?
91 (or 98) elements are naturally occurring.
What are the parts of Dalton’s Atomic Theory?
- Elements are composed of small indivisible particles called atoms
- All atoms of an element are identical
- Atoms of a given element are different from atoms of other elements
- Compounds are formed by combinations of atoms of two or more elements
- Chemical reactions are due to rearrangements of atoms.
Who discovered the electron?
JJ Thomson.
What is Thomson’s Plum Pudding Model?
Atoms contain electrons embedded in a positive ‘pudding’ substance.
What is an alpha particle?
It has two protons and two neutrons; it is the nucleus of a helium atom.
What did Rutherford’s experiment demonstrate about the atom?
The atom is mostly empty space with a small dense positive nucleus.
What is an isotope?
Atoms with the same number of protons and electrons but varying in the number of neutrons.
What evidence from Thomson’s experiment shows that all atoms contain electrons?
- Particles were attracted to the + electrode
- Deflected by magnetic fields
- Deflected by electrical fields
- Identical regardless of the identity of the cathode.
Why are neutrons harder to detect?
They are neutral in charge and reside in the nucleus.
What is a scientific model?
A drawing, graph, diagram, or equation that helps us make sense of and predict phenomena.
Fill in the blank: A _______ contains more than 2 atoms.
Molecule
Fill in the blank: A _______ contains more than 2 types of elements.
Compound
True or False: All compounds are molecules.
True.
True or False: All molecules are compounds.
False.
