Atomic Structure Flashcards
How to classify elements
What is everything in the world made up of?
How many types of atoms does each element contain
What are atoms
Everything in the world is made from about 100 elements.
Each element contains only one type of atom.
Atoms are the tiny particles from which everything is made.
Non metals on the periodic table
The non metals on the periodic table are found on the right side of the table.
Solid liquid or gases
Examples of elements
Three elements which are solids at room temperature are magnesium, aluminium and sulphur.
Three elements which are gases at room temperature are hydrogen, oxygen and chlorine.
The only two elements which are liquids at room temperature are bromine and mercury.
Naturally occurring or man-made in the data booklet
The man-made elements have an asterisk beside their symbol on page 8 of the National 5 Chemistry Data Booklet.
How the periodic table is arranged
The periodic table is arranged in columns known as Groups and rows known as periods.
The structure of an atom
The protons and neutrons exist in a very small, dense core at the Center of the atom. This is called the nucleus.
The electrons are spread out around the edge of the atom. They orbit the nucleus in layers called shells. What
Properties of protons, neutrons and electrons.
Two properties of protons, neutrons and electrons that are especially important:
•Relative mass
•Electrical charge
Particle Mass Charge
Proton 1 +1
Neutron 1 1
Electron Almost 0 -1
The atoms of an element have no overall charge as the positive charge of the protons in the nucleus is equal to the sum of the negative charges of the electrons.
What is the Atomic number
The elements in the Periodic Table have a number called the atomic number which increases from left to right across the table.
This number tells us how many protons an atom has.
As all atoms are neutral the number of protons must equal the number of electrons.
The number of protons in an atom is called its atomic number
What is Mass number
The mass of an atom is due mostly to the total number of protons and neutrons it has in its nucleus.
This mass is given by the element’s mass number.
Mass number = number of protons + number of neutrons
Therefore, as the atomic number is the number of protons in an atom: Mass number = atomic number + number of neutrons
If we know the mass number and atomic number we can use this to work out how many neutrons are in an atom of the element:
Number of neutrons = Mass number - Atomic number
Describe Alkali Metals
The elements in group 1 are known as the alkali metals.
They react rapidly (very fast) with water, producing an alkaline solution and hydrogen gas.
As you go down the group the elements become more reactive. Examples include: Lithium, sodium and potassium
Describe Group 2: The Alkali Earth Metals
These elements include magnesium, calcium and barium.
They burn brightly and react with oxygen to form oxides. The oxides form alkali solutions with water.
Magnesium + oxygen magnesium oxide Magnesium oxide + water magnesium hydroxide
Describe Group 7: The Halogens
The elements in group 7 are known as halogens.
Fluorine and chlorine are gases. Bromine is one of only two liquid elements. Iodine is solid.
As you go down the group the halogens become less reactive.
Describe Group 0: The Noble Gases
The elements in group 0 are called the noble gases.
They are very unreactive and exist as individual atoms (monatomic). Examples include: Helium, neon and argon.
Describe The Transition Metals
The transition metals are elements which are found between groups 2 and 3. They do not have their own group number.
Well known examples are iron, copper and gold.
They are generally quite dense (heavy) and many form brightly coloured compounds
Describe Ions
In some compounds, electrons have been transferred from one atom to another.
This means that it will be negatively charged if it has gained electrons, positively charged if it has lost electrons. These particles are called ions.
Metals lose electrons and become positive ions.
Non-metals usually gain electrons and become negative ions.
When an atom becomes an ion it has the same electron arrangement as one of the group 0 elements (for example neon).
