Atoms Flashcards
What groups of the periodic table do we know?
- Alkali metals - group 1
- Alkaline Earth Metals - group 2
- Transition Metals - Scandium to Zinc
- Halogens - Group 7
- Noble Gases - Group 8 (0)
Where is the separation between metals and non-metals?
Hydrogen / Boron until Astantine
Are noble gases reactive?
No
Why are the noble gases not reactive?
Noble gases have a full outer shell in their natural form, hence they do not seek to gain or lose one electron to achieve a positive or negative ion, and do not react. However, substances that do not react are the substances more commonly used in our everyday lives.
Which groups increase in reactivity as you go down the group?
Group 1 and 2
Why does Group 1 and 2 increase in reactivity?
Group 1 or 2 atoms seek to lose 1 or 2 electrons for a full outer shell respectively. However, as lithium only has 2 outer shells, as opposed to francium with 7 outer shells, it is much easier for francium’s outer electron to overcome the attractive force to the nucleus compared to lithium’s outer electron. Hence, as the period number or number of outer shells increases, so does the reactivity.
What are the most reactive metals?
Group 1 metals, as they only have to lose one electron to gain a positive ion
What are the most reactive non-metals?
Group 7, as they only have to gain one electron to gain a negative ion.
Why do the halogens decrease in reactivity as you go down the group?
As you go down the group, they are more electron shells, hence it is harder to gain an electron as the nucleus is farther away from the outer shell, and the attractive force to the nucleus weaker at this distance, as opposed to fluorine, which is highly reactive as the nucleus is much closer to the free or delocalised electrons.
Which elements conduct electricity?
Metallic elements
Which elements do not conduct electricity?
Non-metallic elements
What non-metal can conduct electricity?
Carbon is a good conductor
Metals Vs Non-metals
Metals
High melting and boiling points (all except mercury solid at room temperature)
Good conductors of electricity and heat
Malleable (change shape when hit)
Shiny when polished
Dense (heavy)
Three metals are magnetic (iron, cobalt and nickel)
Non-metals
Low melting and boiling points (many are gases at room temperature)
Poor conductors of electricity (except graphite - a form of carbon)
Brittle (break when hit)
Dull
Less dense
None are magnetic
Mercury
Mercury is the only metal that is liquid at room temperature. It is extremely heavy and releases a toxic vapour, and it used to be used for thermometers, as opposed to alcohol. It used to be used for hats or felt, but this led to people getting mercury poisoning (Mad Hatter).
What is an atom?
Atoms are the simplest particles that can exist on their own. The word ‘atom’ originates from the Greek word meaning ‘unsplittable’. Atoms are very small, the smallest is 1 x 10^-8 mm across.
Elements
There are about 100 different elements, but more are discovered by merging different atoms.
Are the shells spherical?
The first shell is a sphere, but, beyond this, they are no longer spherical.
What is 1 amu?
1 atomic mass unit (the weight of a hydrogen atom)
Structure of an atom
An atom has a small central nucleus, composed of protons and neutrons, and the electrons are located in shells around it.
Components of an atom
Name of particle Where? Charge Mass (in amu)
Proton Nucleus Positive (+1) 1
Neutron Nucleus Neutral (0) 1
Electron Outer shells Negative (-1) 1/1800 (n/a)
In atoms
number of protons = number of electrons (atoms are neutral)
the number of protons is called the atomic number
protons + neutrons is the atomic mass
neutrons = atomic mass - atomic number
What increases as you go through the periodic table?
Atomic Mass
What is the period number equal to?
The number of outer shells an atom has
What is the group number?
The number of outer electrons an atom has
What is the shell electron capacity?
2, 8, 8, 18
nth term = 2(n^2)
Draw the electronic structure of chlorine
N/a
What is the electronic arrangement of sodium
2, 8, 1
What is an isotope?
Atoms of an element with the same number of protons but a different number of neutrons.
Does an isotopic element affect chemical reactivity?
No, chemical reactions involve the electrons in an atom and have nothing to do with the neutrons, therefore there is no difference in the chemical reactivity of different isotopes of the same element; isotopes can only be distinguished from the mass.
How many neutrons does Hydrogen 3 have?
2
How many neutrons does Oxygen 18 have?
10
What is another way to represent the relative atomic mass?
Ar
What is the use of RAM?
It compares the mass of the atoms of an element with atoms of the carbon-12 isotope, as it is easy to store and is cheap.
What is the relative atomic mass?
It is the average mass of all the atoms of an element. Usually this is just taken to be the mass of the most common isotopes, but when two or more isotopes are present in large amounts then a weighted average is calculated, or relative atomic mass.
Relative atomic mass formula
(mass of isotope x % of isotope) + (mass of isotope x % of isotope) / 100
Calculate the relative atomic mass of silver:
55% 107Ag
45% 109Ag
RAM = (107 x 55) + (109 x 45) / 100
= 107.9
