2.1 - Matter Flashcards
What are atoms made up from?
Subatomic particles; protons, neutrons and electrons
What makes up the nucleus of an atom?
Protons and Neutrons
What do electrons orbit around a nucleus of an atom in?
Shells
Electrons in the closest shell to the nucleus have the _____ amount of energy whereas the electrons in the outer most shell have the _____ amount of energy.
Electrons in the closest shell to the nucleus have the LEAST amount of energy whereas the electrons in the outer most shell have the HIGHEST amount of energy.
What does Subatomic mean?
‘Smaller than an atom’
How small are electrons in comparison to protons and neutrons?
Nearly 2000 times smaller
What is an elements atomic number?
It’s number of protons. It’s used to arrange the elements in the periodic table.
Who published the first widely recognised periodic table of elements?
Dmitri Mendeleev in 1869
They were arranged in order of the properties of the then-known elements.
What group number are halogens?
Group 17
What group number are noble gasses?
Group 18
What does the group number (vertical column) signify?
The number of electrons in the outer shell.
What is the difference between a mixture and a compound?
A mixture isn’t chemically bonded together meaning it can be easily divisible back to original elements by physical means, but a compound is chemically bonded together meaning it can only be divisible back to it’s elements by chemical processes.
What is Chemical Synthesis?
The name given to the purposeful execution of chemical reactions to obtain a compound.
What is the process of a chemical reaction to break down (splitting) a compound into it’s constituent elements called?
Chemical Analysis,
Decomposition, or;
Breakdown
How many elements are known today?
There are at least 118 elements in our known universe.
What is a molecule?
A combination of two or more atoms connected in a fixed ratio that act as a single unit. They have been chemically bonded with each other.
What does Diatomic and Triatomic mean?
Diatomic - a molecule made up of two of the same atoms bonded together (O2)
Triatomic - a molecule made up of three of the same atoms bonded together (O3)
What are the reactants in a chemical reaction?
The substances initially involved in a chemical reaction
What is added to a chemical reaction (apart from heat) that will increase the rate of the reaction?
A catalyst; an additional chemical added to increase the rate of the reaction
What is an inhibitor?
Opposite of a catalyst; also known as “negative catalysts” because they decrease reaction rates
What is the atomic number also known as?
The proton number (Z)
What is the mass number?
The atomic mass number is the nucleon number (A) (number of protons and neutrons)
How do you work out the number of neutrons in an isotope?
The difference between the mass number and the atomic number
What is the AMU?
Atomic mass unit
What is the atomic mass defined as?
1/12 the mass of an atom of carbon-12.
What is an isotope?
It is an atom of an element with more than it’s original number of neutrons.
What are the symbols for the electron shells?
1st - K (2)
2nd - L (8)
3rd - M (18)
4th - N (32)
What is the formula for electron shells?
2n(^2)
What is Pauli’s exclusion principle?
2n(^2) The electron shell principle
What are the electron subshell levels?
s, p, d, and f
What is ionization?
The loss or gain of electrons to an atom
What is a Cation?
A positively charged ion.
What is a Anion?
A negatively charged ion.
What is Valency?
An atom’s valency is how well it will chemically combine to another atom. It depends on the number of electrons present in the most outer shell.
The normal valency of an atom is equal to the number of outer electrons if it is 4 or less; otherwise valency is equal to 8 minus the number of outer electrons.
What is special about atoms with 4 electrons in their outer shell?
They are semi-conductors
What happens to the electrons in the outer shells in a conductor?
They are free to move through the material.
What is an Amorphous material?
A material in which atoms are placed at random.
How does resistance change with temperature in a semiconductor?
Resistance decreases as temperature increases (opposite to that of a metal)
What is the structure of a semiconductor?
A crystal lattice structure
What is special about semiconductors? (tetravalent)
They have 4 electrons in their outer shell.
What is Coehsion?
The intermolecular force between liquid particle types (what makes water molecules stick together)
What is Adhesion?
The intermolecular force between dissimilar atoms (temporary)
Why are noble gasses reluctant to combine with other atoms?
They have very stable electron arrangements (2, 2.8, 2.8.8)
What is Covalent bonding?
It’s a form of chemical bonding where electrons are shared to form molecules. Usually between two non-metallic elements.
What are small covalent molecules sometimes referred to as?
Molecular covalent bonding
What is a valence shell?
The most outer electron shell
What is sublimation?
When a solid becomes a gas without ever becoming a liquid.
What is deposition?
When a gas becomes a solid without going through the liquid phase.
What is the random movement of both liquids and gasses known as?
Brownian motion
What colour does universal indicator paper turn when testing for an acid?
From green to red
What colour does universal indicator paper turn when testing for an alkali?
From green to blue/purple
What is the pH scale?
The strength of an acid or alkali solution. Number from 0-14.
Acidic 0-6
Neutral 7
Alkaline - 8-14
What is the size of an atom in the order of magnitude of?
The nanometer
