Atoms and Molecules Flashcards
What is the definition of ‘matter’?
A physical substance that occupies space that has mass - everything that is made of matter is a chemical
What is the definition of ‘chemical’?
A chemical is produced by or used in a reaction involving changes in atoms or molecules.
It is also a substance used in chemistry or produced by a process involving chemistry.
Everything made of matter is a chemical.
What is an ‘element’ ?
An element is a substance that consists of only one type of atom.
It is the basic building block of matter e.g. Hydrogen (H) oxygen (O) Nitrogen (N) Carbon (C)
What is ‘chemistry’ ?
Chemistry is a scientific study of the structure of substances and the way they react to other substances.
What is a ‘compound’?
A compound are chemicals that comprise of more than one basic element e.g. Water, which is made from hydrogen and oxygen
Salt, sodium chloride
What does an ‘atom’ consist of?
It consists of a nucleus made of protons and neutrons with electrons traveling around it.
What is an ‘atom’?
It is the smallest unit of any substance.
What is a ‘molecule’?
A molecule is a group of two or more atoms that stick together
Is a water molecule linear? (I.e. In a straight line) or bent?
Water molecules are bent, the atoms are not connected in a straight line
What is an electric charge?
It is the property of matter that causes electrical phenomena
Are atoms positive or negative?
They are neutral
If an atom can be shown to contain negative particles (that is electrons) what else must there be in an atom?
There must be some particles carrying a positivw charge to balance the negative charge of electrons.
What must happen so that an atom has a net charge of zero?
The total negative charge of the electrons must be balanced by the total positive charge in the protons
What are protons?
The are the positive charged particles in atoms
What is an electron?
It is the negative charge in an atom
What is the relationship between the number of protons in an atom and the number of electrons in the same atom?
Since they have the same charge, but opposite signs there must be the same number of protons as electrons
What determines the identity of each element?
The number of protons
What happens if the number of protons increase in an element?
The mass of the atom increases
What is the atomic number?
It is the amount of protons present in each atom
What is the atomic mass number?
It is the amount it is approx equivalent to the number of protons and neutrons in the atom (the mass number)
How would you work out how many neutrons are present in the atom of an element?
You would minus the amount of protons (atomic number) from the relative atomic mass
What is a neutron?
It is an electrically neutral partial in an atom
What is the relative mass of both a proton and a neutron?
1
How much bigger is the mass of a proton and a neutron to that of an electron?
1840 times that of an electron
Does hydrogen contain neutrons?
No
Why is hydrogen so light ?
Because it basically only comprises of one proton and one electron
(No neutrons)
What is the relative atomic mass of an element?
It is the measure of the mass of one atom of that element.
What is static electricity?
It is electricity produced by friction
How does rubbing objects produce static electricity?
It transfers large numbers of tiny electrons between initially neutral objects causing one to become positively charged (by losing electrons) and the other one negatively charged (by gaining electrons
Explain how scientists picture an atom?
Scientists picture and atom as comprising a central atomic necleus (which contain protons and neutrons) with electrons moving around it at high speed in random directions
What is an isotope?
It is a radioactive form of an element
Contains the same atomic number because it has the same number of protons
But has different number of neutrons
Therefore a different mass
Explain the structure of an oxygen atom?
The nucleus contains eight protons and eight neutrons
Moving outwards there is a space before you can see electrons are randomly moving around it
In the first set there can only be 2 sets of electrons
And again a small space where you then meet 6 electrons
The nucleus of an oxygen atom contains 8 protons which each have a charge of …?
+1
The eight electrons circling around around the nucleus of the oxygen atom each have a charge of …?
-1
The overall charge of an oxygen atom is…?
Zero
What are the two most common ways atoms can bond together?
Covalent bonding
Ionic bonding
What is a chemical bond?
It is the interaction of electrons of one atom with those of another
What is covalent bonding?
It is one kind of linking between atoms where electrons are shared by two nuclei
How is a water molecule bonded?
A water molecule is bonded covalently as the electrons are shared by two nuclei
How many electrons are shared by both a hydrogen atom and a oxygen atom in the bonding of a water molecule?
Two electrons are shared between the oxygen and each hydrogen. This is called a single bond
What is a compound molecule?
When two or more different atoms link together
What is a double bond?
It is when two atoms share 4 electrons
Define the term chemical formula of a covalent compound?
The chemical formula of a covalent compound shows the number of each type of atom in one molecule of the compound
It is usually written using the symbols for the elements
What is the chemical formula of oxygen?
O2
Oxygen gas in the air does not exist in the form of free individual oxygen atoms.
What is the chemical formula of table salt?
NaCl
Is common salt or sodium chloride
What is intramolecular attraction?
It is the attraction within a molecule (chemical bonds holding the atoms together)
What is intermolecular attraction?
Attraction occurring between a molecule
Which atoms are more attracted to each other in water molecule?
Hydrogen atoms are more attracted to the oxygen atom
If the electrons are pulled more towards the oxygen atom than to the hydrogen atoms what do you think happens to the charge distribution?
There will be a separation in charge between the oxygen atom (becoming more negative) and the hydrogen atoms (becoming more positive)
What is the term polarisation commonly used to describe?
The partial separation of charge
E.g. Certain atoms with have a slightly more/less positive/negative charge than another
The charge is not equal e.g. Water molecule the oxygen has a slight negative charge and the hydrogen a slight positive charge this causes the hydrogen atoms to constantly be moving around and attracted to other water molecules
The attraction between the molecules is called hydrogen bonding
How can polarisation be represented?
Delta minus
Delta plus
What does the term delta mean?
A little bit, since its amounts are less than an electrons worth
What is a polar bond?
It is when one atom has a partial negative charge and another has a partial positive charge … this causes one to be more attracted to another
Why do covalent bonds between two different elements always present some polarisation?
Because the atomic numbers are different so one will attract more than another
Is the covalent bond between two atoms of the same element polar or non polar?
The covalent bond between two atoms of the same element is non -polar because both atoms attract the shared electrons to the same extent
What is a hydrogen bond?
It is is the attraction of the positive hydrogen atom of one water molecule attracted towards the negative oxygen atom of another water molecule
Do water molecules have polar or non-polar bonds?
They can have both
If these bonds are evenly distributed,
Hydrogen atoms are attracted to oxygen atoms by a polar bond but when they are together the hydrogen is attracted to the negative oxygen of another water molecule
Are hydrogen bonds intermolecular or intramolecular?
Hydrogen bonds are intermolecular bonds
Does hydrogen exist as a single atom?
Hydrogen (and oxygen) do not exist as single atoms
What is the chemical equation for the production of water?
2H2(g) + O2(g) = 2H2O(l)
How many molecules of water are formed when one molecule of oxygen reacts with two molecules of hydrogen?
Two molecules of water are formed when one molecule of oxygen reacts with two molecules of hydrogen.
What are the three states of matter written for a chemical equation?
S for solid
L for liquid
G for gas
What happens when chemical substances/reactants are mixed together?
It creates a new chemical substance
Product
What are reactants?
They are chemical substance/compounds that when mixed together make a new chemical substance
What is a ‘product’ in terms of chemical reactions?
It is the new substance that is made from the reactants (chemical substances/compounds) are mixed together
