1) Key Concepts in Chemistry Flashcards
What are compounds?
Combined atoms of different elements
What is the smallest piece of an element that can exist?
An atom
What are the key features of chemical compounds?
Compounds are broken up or formed
At least 1 new substance is created
Measureable energy change
No atoms are created or destroyed
What type of equation must be balanced?
Symbol equations
What is the order of atomic models?
Dalton’s model
Thomson’s plum pudding
Rutherford’s nuclear model
Modern model
What is the atomic number?
Number of protons in the atom
What is the mass number?
Number of protons + neutrons
What is the top number of an atom?
Mass number
What are isotopes?
Atoms with the same number of protons but a different number of neutrons
What are the isotopes of hydrogen?
Protium
Deuterium
Tritium
What is the name for a specific nucleus that contains a certain number of protons and neutrons?
Nuclide
What did J.J.Thomson discover?
Electrons
What was J.J.Thomson’s model?
Plum pudding model
What did Rutherford discover?
Alpha particles could bounce off atoms
Atom’s mass concentrate in centre
Protons
What was Rutherford’s model?
Nuclear model
Who discovered neutrons?
James Chadwick
What is the relative atomic mass?
The average mass of all of the isotopes of an element
What is the formula for Ar?
(Isotope abudance x isotope mass number) / isotope abundance
What does Ar mean?
Relative atomic mass
What is the isotope abundance?
How often each isotope of an element is found
What are the rows of the periodic table called?
Periods
What are the columns of the periodic table called?
Groups
What does the group number equal?
The number of electrons in an atom’s outer shell
Who was the first to devise a periodic table?
John Newlands
Who predicted the undiscovered elements of the periodic table?
Mendeleev
How do we rank elements today?
By their atomic number (number of protons)
Where are metals found on the periodic table?
The left side
What happens when metals react?
They lose 1 or more electrons to form positive ions
What are properties of metals?
High melting and boiling points
Good conductors of heat and electricity
Solids at room temperatrue (except mercury)
Where are non-metals found on the periodic table?
The right side
What happens when non-metals react?
They gain electrons to form negative ions
Or share electrons to form neutral molecules
What are properties of non-metals?
Lower melting and boiling points than metals
Often found as gases
Generally do not conduct heat or electricity
How does energy change as you get closer to an atom’s nucleus?
Closer to nucelus = lower energy level
What is the filled electron configuration?
2,8,8
What is the difference between molecules and an element?
Molecules are a substance with two or more atoms (O2)
Elements are pure substances of the same atom (O)
What can dot and cross diagrams show?
Electrons being transferred and ions formed
What do square brackets and a charge represet in dot and cross diagrams?
Ions
What is a cation?
A positive ion
What is an anion?
A negative ion
What does a cation have?
More protons than electrons