UNIT 1 Flashcards
What are isotopes?
Isotopes are atoms of the same element that have the same atomic number but a different mass number
What is Relative Atomic Mass (RAM)?
It is the average mass of the atoms in an element taking into account the different isotopes and their relative abundance
What are elements in the periodic table arranged in?
They are arranged in atomic number
How are ions formed?
They are formed when atoms gain or lose electrons
What happens if an atom gains an electron?
It becomes a negatively charged ion
What happens if an atom loses an electron?
It becomes a positively charged ion
What do atoms achieve by forming ions?
They achieve the same electron arrangement as the nearest Noble Gas
What are Diatomic molecules made up of?
They are made up of only two atoms
What are the 7 diatomic elements?
Oxygen, Fluorine, Chlorine, Nitrogen, Hydrogen, Iodine, Bromine
How are atoms joined together?
They are joined together by bonds
What are atoms?
They are the building blocks which make up everything in the universe
Why do atoms bond?
Atoms bond to achieve the most stable outer electron arrangement-a full outer shell
What is a covalent bond?
A covalent bond is 2 positive nuclei held together by their common attraction for the shared pair of negative electroms
What are covalent bonds formed between?
2 non-metals
What do you need to break a covalent bond?
Lots of energy as they are extremely strong forces of attraction.
How do atoms form bonds?
By using the electrons in their outer most energy level
What do bonding diagrams do?
They give a simplified picture of an atoms outer electrons
What is everything in the world made out of?
118 elements
What do molecules exist in?
3 dimensions
What does the shape of a covalent molecule depend on?
The number and orientation of central bonds around the atom
How can you show the shape of a molecule?
By using a perspective drawing
What are the 3 types of perspective bonds?
—straight
—> wedged
- - > dashed
What are the diagram names for elements with different numbers of substances?
If there is 1 substance present: linear
If there is 2 substance present: angular
If there is 3 substance present: trigonal pyramidal
If there is 4 substance present: tetrahedral
What is a proton?
A proton is a positively charged particle with a mass of 1 amu, and it is located in the cell nucleus
What is an electron?
An electron is a negatively charged particle with a mass of nearly 0 amu, and it is found orbiting the nucleus
What is a neutron?
It is a particle with a neutral charge which is found in the nucleus of a cell, it has a mass of 1 amu
What are atoms made up of?
Protons, neutrons, electrons
What is broken when covalent molecular compounds melt or boil?
The weak intermolecular forces are broken
What is left intact when covalent molecular compounds melt or boil?
The strong covalent bonds are left intact
If less energy is required in melting covalent molecular compounds…
Less energy required = low melting and boiling points
What do Covalent Networks exist as?
They exist as giant network structures held together by covalent bonds
If lots of energy is required to break the strong covalent bonds…
Lots of energy = high melting and boiling points
How much energy is required to make strong covalent bonds?
LOTS
What does each element have?
A name and a symbol
The alkali metals are?
-Very reactive
-Soft (can be cut with a knife)
-Are stored under oil
-React with water to form an alkaline solution
-React with oxygen to form metal oxides
The transition metals are?
-Hard and Dense
-Less reactive than the alkali metals
-Used in Catalysts
-Form coloured comounds
The Halogens are?
-Diatomic Elements
-All toxic
-Fluorine added to toothpaste to prevent decay
-Iodine used to treat wounds
-Chlorine used to sterilise swimming pools
The Noble Gasses are?
-The least reactive group of elements
-Not reactive at all
Where is the mass number of an element?
On the top
Where is the atomic number of an element?
At the bottom
If atoms of the same element bond what do they become?
They become a molecule of that element
What can covalent substances form?
They can form either discrete molecular or giant network structures
What does the Chemical Formula of a covalent molecular substance give?
It gives the number of atoms present in the molecule
Can different elements form a different number of bonds?
Yes
What is valency?
Valency is the atoms ability to combine with other atoms
What are 1-7 in Roman Numerals?
1- I
2- II
3- III
4- IV
5- V
6- VI
7- VII
What does SVSDF stand for?
Symbol
Valency
Swap
Divide
Formula
What are the prefixes for 1-7?
Mono-1
Di-2
Tri-3
Tetra-4
Penta-5
Hexa-6
Hepta-7
What does ionic bonding occurs between?
Between a metal and a non-metal
What is an ionic bond?
It is the electrostatic force of attraction between positive and negative ions
What is an ionic lattice?
It is a giant arrangement of ions held together by electrostatic attraction
What do ionic lattices consist of?
They consists of millions of ions held together in a lattice by ionic bonds
How do you break strong ionic bonds?
With lots of energy
What are ionic compounds at room temperature?
They are always solids at room temperature
What does the formula of an ionic compound give?
It gives the simplest ratio of ions in a substance
What does ionic formula show?
It shows the charge on each of the ions
What is a group ion?
It is an ion which contains more than one type of atom
What is an electrical current?
It is a flow of charged particles
What do electrical conductors allow?
They allow electrical currents to flow through them
What do non conductors not allow?
They don’t allow an electrical current to flow through them
What elements conduct electricity?
Metal elements and carbon (in the form of graphite)
Why can metals conduct electricity?
Because electrons can flow through them
What do atoms share in covalent bonds?
They share a pair of electrons
Is electricity conducted in covalent bonds?
No, because the atoms share a pair of electrons, therefore the electrons are not free to move about
Describe the outer electrons of metal atoms?
They are not attached to a particular atom and are free to move about. They are delocalised
Do non-metals conduct electricity?
No, because they don’t have charged particles that can move
What does carbon in the form of Graphite have?
It has a layered covalent network structure
What does a carbon atom use for bonding?
It uses only 3 electrons and the remaining electron is delocalised over the whole structure
Why can graphite conduct electricity?
Because electrons can flow through it
Do covalent compounds conduct electricity?
NO
Do ionic compounds conduct electricity in the solid state?
No, because the ions are not free to move
When do ionic compounds conduct electricity?
When dissolved in water or when molten
What happens when ionic compounds dissolve in water?
The lattice breaks, and the ions are free to move, therefore the conduction of electricity can occur
What do covalent substances which are insoluble in water dissolve in?
They dissolve in other solvents
What are many ionic compounds soluble in?
Water
Do covalent network substances dissolve?
No
What happens as covalent molecular substances dissolve?
The lattice structures break up allowing water molecules to surround the seperated ions
What are discrete covalent molecules?
Small groups of atoms held together by covalent bonds
