Chapter 1 - Atomic Theory Flashcards
What is matter?
anything that has mass and occupies space (i.e. has volume)
WHat are atoms?
basic submicroscopic particles that constitute the fundamental building blocks of ordinary matter
What are molecules?
substances formed when 2 or more atoms come together (bond) in specific geometric arrangements
How many and what states does matter exist in?
3 - solid, liquid, and gas
If matter is made up of only one type of particle what is it?
a pure substance
If matter is made up of more than one type of particle what is it?
a mixture
If a pure substance can be separated into simpler substances what is it?
a compound
If a pure substance cannot be separated into simpler substances what is it?
an element
If a mixture is uniform throughout what is it?
Homogenous
If a mixture is not uniform throughout what is it?
Heterogenous
What does Homogenous mean?
two particles that thoroughly mix (like tea and sugar)
What does Heterogenous mean?
two types of particles that separate into distinct regions
What is the law of conservation of mass?
in a chemical reaction, matter is neither created or destroyed
What is the law of definite proportion?
all samples of a given compound, regardless of their source or how they were prepared, have the same proportions of their constituent elements
What is the law of multiple proportions?
when 2 elements (A and B) from 2 different compounds, the masses of Element B that combine with 1g of element A can be expressed as a ratio of small whole numbers
What is Dalton’s Atomic Theory? (4 points)
from the 1800s
each element is composed of tiny , indestructible particles called atoms
all atoms of a given element have the same mass and other properties that distinguish them from the atoms of other elements
Atoms combine in simple whole number ratios to form compounds
Atoms as one element cannot change into atoms of another element
What did J.J. Thompson do?
Cathode Ray experiment
What is a Cathode ray?
a beam of small particles
What are the 3 properties of cathode rays?
They travel in straight lines
They are independent of the material from which they originate
They carry a negative electrical charge
What did the Cathode ray experiment discover?
Electron and oits charge to mass ratio (-1.76 x10^8 Coulombs (C) per gram)
What did Millikan’s drop oil experiment discover?
Electron mass (0.109382 x10^-28g)
What model did J.J. Thompson propose?
The plum pudding model - electrons held randomly within a positively charged sphere
What happened to some of the rays in Ernest Rutherford’s Gold foil experiment?
some of the alpha radiation rays deflected
What did these deflected rays suggest?
That there was a small region of very dense matter in the atom
WHich atom model was suggested because of Ernest Rutherford’s experiment?
The Nuclear Atom Model
What does the nuclear atom model contain?
a nucleus: a small core at the atom’s centre that contains most of the mass (all positive charge)
Electrons: dispersed throughout the empty space around the nucleus (negatively charged)
Charge Neutrality: the number of negatively charged electrons outside the nucleus is equal to the number of positive particles (protons) within the nucleus.
What is Avagadro’s constant?
one mole contains 6.02214x10^23 particles
What is an Isotope?
when the number of neutrons varies
What is the mass number (isotopes)?
the number of protons + number of neutrons
What is the atomic number (isotopes)?
the number of protons
Can elements have a positive or negative charge?
yes, they are then called ions. they have lost or gained electrons
How do you calculate atomic mass?
Sum of: (fraction of isotope n) * (mass of isotope n)
How many particles does 1 mole contain?
6.02214 x 10^23
