Atoms, Elements and Compounds Flashcards
What is an element?
An element is made up of only one type of atom. It cannot be broken down into anything simpler.
What is a compound?
Two or more elements chemically bonded in a fixed ratio.
This makes them difficult to separate and therefore need to undergo change if this were to happen.
What is a mixture?
Two or more elements OR compounds that are not bonded and in a variable ratio.
What are molecules?
Molecules are made up of 2 or more atoms of the same or different elements chemically bonded together
What is the difference between a molecule and a compound?
Molecules can be made up of two atoms of the same kind.
All molecules are not compounds but all compounds are molecules.
Which change is harder to reverse - chemical or physical?
Chemical
Sodium chloride is a compound made from sodium and chlorine. Sodium fizzes when added to water. Explain why sodium chloride does not fizz when added to water.
After being chemically bonded to make a compound, some characteristics may not remain anymore as it is a completely different substance.
What is an electron?
An electron is a subatomic particle found in shells (energy levels) around the nucleus.
What is the charge of an electron?
Negative
What is the charge of a proton?
Positive
What are the characteristics of an electron?
- They have almost 0 mass
- Can be lost or gained in a reaction
- Found in shells
- Negatively charged
Choose the correct option for the following:
Metals are shiny/not shiny
Metals have a high/low melting point
Metals are malleable/not malleable
Metals are ductile/not ductile
Metals are good/bad electrical conductors
Metals are good/bad thermal conductors
Shiny
High
Malleable
Ductile (ability to be stretched into wire)
Good
Good
Choose the correct option for the following:
Non-Metals are shiny/not shiny
Non-Metals have a high/low melting point
Non-Metals are malleable/not malleable
Non-Metals are ductile/not ductile
Non-Metals are good/bad electrical conductors
Non-Metals are good/bad thermal conductors
Not shiny
Low
Not malleable
Not ductile
Bad
Bad
What is the relative mass and relative charge of:
-a proton
-a neutron
-an electron
Proton: 1 and +1
Neutron: 1 and 0
Electron: almost 0 and -1
What does the atomic number represent on the periodic table?
Amount of protons
Amount of electrons
What does the mass number represent on the periodic table?
The sum of protons and neutrons
How do you work out the number of neutrons?
Mass number - Atomic number
What determines what type of atom it is?
The amount of protons
What is an isotope?
An atom that has the same number of protons but a different number of neutrons.
They have the same atomic number but different mass number.
E.g. Carbon: C-12 C-13 C-14
Why are C-12 C-13 and C-14 all still considered atoms of carbon despite being different?
They all still have 6 protons
How would you simply describe what the Relative Atomic Mass is?
The average mass of an atom.
How do you work out the relative atomic mass?
Ar = (mass number x percentage) + (mass number x percentage) /100
How many electrons can the first second and third shells (energy levels) hold?
2,8,8
What do the rows of the periodic table tell you about the elements?
How many shells there are
E.g. Potassium, third row, has 3 shells
What does the column number tell you about an element?
What group the element is in and how many electrons are in the outer shell.
Why is group 0/8 noble gases unreactive?
They already have a full outer shell which is the desired outcome. Other elements need to gain or lose electrons to get a full outer shell so they need to have a reaction. As noble gases don’t need to have a reaction, they do not need to be reactive.
