Matter/Chemical Change - Section 2 Flashcards
What is the smallest unit of matter?
Atom
What are the points of the Atomic Theory?
All matter is made up of atoms
Atoms of one element are different from atoms of another element
Atoms may combine with other atoms to form larger particles called molecules
Atoms cannot be created or destroyed by ordinary chemical means
What are atoms?
The smallest independent particles of an element that can exist in nature
Atoms are made up of three ________ _________
Subatomic particles
What is a proton?
Positive charge, found in the nucleus, approximately half the mass of the atom
What is a neutron?
Neutral charge, found in the nucleus, approximately half the mass of the atom
What is an electron?
Negative charge, found orbiting the nucleus, very little mass
In an atom, the number of __________ must equal the number of ____________
Protons, electrons
Describe John Dalton’s atom model.
Billiard ball model - he thought the atoms as tiny spheres
Describe JJ Thomson’s atom model.
Raisin bun model - he thought of the atom as a positively charged sphere with negatively charged electrons embedded within it
Describe Hantaro Nagaoka’s atom model.
Solar system or Saturn ring model - negatively charged electrons orbiting around the large positive charge
Describe Ernest Rutherford’s atom model.
Planetary model - negatively charged electrons orbit around the positively charged nucleus
Describe Niels Bohr’s atom model.
Electron shell model - the electrons orbit around the nucleus in specific shells
Describe James Chadwick’s atom model.
His model is identical to Bohr’s but the nucleus is shown to have neutrons along with the protons
What did John Dalton discover about the atom?
He was the first to define an element as a pure substance containing no other substances
What did JJ Thomson discover about the atom?
He discovered the electron
What did Hantaro Nagaoka discover about the atom?
He refined Thomson’s model as he did not believe that negatively charged particles are embedded in the positively charged sphere
What did Ernest Rutherford discover about the atom?
Contributed to the development of atomic theory
He also discovered the nucleus
What did Niels Bohr discover about the atom?
Suggested that the electrons do not orbit randomly around the nucleus but instead move in circular orbits or electron shells
What did James Chadwick discover about the atom?
He discovered the neutron
What is the Quantum Mechanical Model?
Describes the atom as a negatively charged cloud of electrons surrounding a positively charged nucleus
What are the columns in the Periodic Table called?
They are called groups or families
The elements in each group have similar properties
What are the rows in the Periodic Table called?
They are called periods
As you move left to right you see an increase in the number of protons and electrons
What is the atomic number of an element in the Periodic Table?
It shows how many protons (and electrons because they are equal) are found in the nucleus of 1 atom of that element
What is the Atomic Mass of an element on the Periodic Table?
The total mass of the protons and neutrons.
Electrons are so tiny that their mass has little effect in the total mass of the atom
What is the mass number in an element on the Periodic Table?
You round the atomic mass to the nearest whole number
How do you find the number of neutrons in one atom of an element?
Mass Number subtract the Number of Protons
What is the staircase line on the Periodic Table?
Divides the metals on the left from the non-metals
Along the staircase line you find the metalloids (except aluminum)
What are the properties of metals on the Periodic Table?
Generally solids Shiny Often a shade of grey Malleable and ductile Good conductors if heat and electricity Many will lose electrons to positive ions
What are the properties of non-metals on the Periodic Table?
May be solids, liquids, or gases
Usually dull
A variety of colours
Brittle
Generally poor conductors of heat and electricity
Many will gain electrons to become negative ions
What are the properties of metalloids on the Periodic Table?
Are elements found along the staircase line
Have properties of both metals and non-metals
Where do you find the atomic number in the Periodic Table?
The top left corner
Where do you find the atomic mass in the Periodic Table?
Underneath the element name
In what group would you find the alkali metals?
Group 1
Not including Hydrogen
In what group would you find the alkaline earth metals?
Group 2
In what group would you find the halogens?
Group 17
In what group would you find the noble gases?
Group 18
