Topic 1- Key Concepts In Chemistry 📄 Flashcards
What is an atom?
Smallest unit of matter
What is an element?
Single type of atom
What is a compound?
2 or more elements chemically bonded together
What is a mixture?
2 or more elements or compounds not chemically bonded
What is a chemical formula?
Shows the numbers of each type of atom in a compound
What is the periodic table?
The table of elements in which all the elements we know are in order of atomic number
Sub-Atomic Particles
What charge does an electron have?
Negative (-1)
Sub-Atomic Particles
What charge does a proton have?
Positive (+1)
Sub-Atomic Particles
What charge does a neutron have?
Neutral (0)
Sub-Atomic Particles
What is the relative mass of an electron?
0 or
1
——
1840
Sub-Atomic Particles
What is the relative mass of a proton?
1
Sub-Atomic Particles
What is the relative mass of a neutron?
1
What is in the nucleus of an atom?
Protons and Neutrons
What is found outside the nucleus & how?
Electrons in shells
Why does an atom have no overall charge?
Because it contains the same number of electrons (-1) and protons (+1)
What is the atomic number?
The number of protons (equal to the number is electrons) in an atom
How do you identify the atomic number?
It is the smaller number
What is the relative atomic mass?
The number of protons and the number of neutrons
How do you identify the relative atomic mass?
It is the higher number
How do you find the number of neutrons?
Neutrons= Relative atomic mass - Atomic number
What do you know about the periodic table? (7)
- Split into periods ( number of electron shells) and groups ( how many electrons are in the outer shell)
- Metals and NON+Metals
- Organised by increasing atomic number
- Includes atomic and relative mass Number
- It contains 118 elements
- Includes symbols
- Dmitri Mendeleev
Where is most of the mass of an atoms found in the atom?
In the nucleus of the atom because protons and neutrons have a relative mass of 1 whereas electrons have a relative mass of 0 so the electrons shells don’t contribute to the overall mass
What is an isotope?
** Atoms of an element that have the same number of protons, but different numbers of neutrons in their nuclei. **
This results in a different atomic mass, but the same mass number
Isotopes of an element have: (2)
> Same atomic number
Different mass numbers
How do you calculate Relative atomic mass?
(Mass number of isotope 1 X percentage abundance of isotope 1) + (Mass number of isotope 2 X percentage abundance of isotope 2)
———————————————
100
What do columns represents on the periodic table?
Groups
What does the group number show on the periodic table table?
The number of electrons in the outer shell of an atom
—> therefore similar chemical properties
Group =
Column
Period =
Row
What does the period tell you on the periodic table?
How many electron shells are in an atom
How do electrons link to the position of an atom on the Periodic Table?
The links are: the number of circles in the electronic configuration of an element is represented in the periodic table as the period number that element is situated in. the number of electrons in the outermost shell of an element is represented in the periodic table as the group number that element is situated in.
How to identify metals and non-metals on the periodic table?
Metals are located on the left of the periodic table, and nonmetals are located on the upper right. They are separated by a diagonal band of semi metals.
Properties of metals:
Most metals share similar properties with each other. For example:
They have high melting and boiling points
meaning they are solid at room temperature
They are good
conductors
of heat and electricity
They are shiny in their appearance
They are malleable
Have a high density
They are sonorous
Properties of non-metals:
Poor conductors of heat and electricity
Dull in their appearance
Weak and brittle
Generally low melting and boiling points, meaning they are gases and liquids at room temperature
Not sonorous
Who was Dmitri Mendeleev ?
Creator of the first periodic table
How did dmitri mendeleev group elements?
According to their properties
What did Mendeleev do with the periodic table?
Left gaps where he thought new elements might be discovered would fit
How do we organise the periodic table?
By increasing atomic number
What is electronic configuration?
The number of electrons that go into each wheel of an atom
How are electrons arranged?
In shells around the nucleus of an atom
How many electrons in the
1st
2nd
3rd
4th
Shell of an atom?
Max 2
Max 8
Max 8
Max 18
