C1 Atomic Theory Flashcards
What is the definition for the word element?
An element is a substance that cannot be broken down into any other substance. Every element is made up of its own type of atom.
Describe the basic structure of an atom.
An atom contains a central nucleus which has neutrons and protons, it also has electrons that orbit the nucleus in fixed shells.
What is the difference between a pure element, mixture and compound?
- An element is a pure substance which contains identical atoms or molecules with only one type of atomic core.
- A compound is a pure substance which contains identical molecules with two or more types of atomic core.
- A mixture is a material which has two or more types of molecules.
Explain the significance of chemical symbols used in formulae and equations.
Chemical symbols are used to standardize the ‘language of chemistry’ and to identify elements and atoms in a chemical formula easily.
Why is mass conserved in a chemical reaction?
Mass is conserved because matter (mass) cannot be created or destroyed.
How may mass appear to change in a chemical reaction?
If a gas escapes, the total mass will look like as if it has decreased.
Why is mass conserved in a chemical reaction?
Because of the law of conservation of mass.
List the order of which the models proposed for atoms were found in.
Solid sphere model
Plum pudding model
Nuclear model
Planetary model
Quantum model
What are the differences between the plum pudding model and the nuclear model.
- The nuclear model has it’s mass concentrated in the middle
- The nuclear model is mostly empty space.
- The nuclear model has its electrons separated from the nucleus.
Why has the model of the atom changed over time?
The model of the time changed over time so that it could explain the new evidence that was found.
What are the key parts of the plum pudding model?
- Atoms consisted of rings of negative electrons embedded in a sphere of positive charge.
- The positive and negative charges make the atom neutral.
- The mass of the atom was due to the nucleus.
What are the key parts of the nuclear model?
- The atom consists mainly of space.
- The mass of the atom is concentrated in the nucleus.
- The nucleus is positively charged.
- Electrons orbit around the nucleus.
- Atoms are neutral as they have the same number of electrons and protons.
What are the masses and relative charges of protons, electrons and neutrons?
Protons: 1 , 1
Electrons: 0, -1
Neutrons: 1 , 0
What is the overall charge of atoms?
Neutral
Explain why atoms have no overall charge.
Atoms have the same number of protons and electrons, so the charges ‘cancel’ each other out.
Explain why can we be confident that there are no missing elements in the first 10 elements of the periodic table.
All of these elements have been confirm discovered by accepted scientific methods.
What is an ion?
An ion is a charged particle that has either gained or lost electrons.
What is an isotope?
An isotope is an element with a different number of neutrons.
Explain why ions have a charge.
If an element loses an electron is because positively charged as there are more protons than electrons. If an element gains an electron the element becomes negatively charged because there are more electrons than protons.
Why does chlorine not have a whole mass number?
This is because of isotopes.
What is the radius of an atom?
1 x 10^-10 m
Where are electrons found in an atom?
Electrons are found in fixed energy levels.
What is the maximum number of electrons in the first 3 energy levels?
2,8,8
How easy is it for group 1 metals to lose an electron as you go down the group?
Atomic Radi increases
Electrostatic attraction between proton / nucleus and outer shell / valence electron decreases therefore the outer shell electron is less strongly held
Shell shielding increases therefore the effect of the nucleus is weaker
Consquently / As a result it is easier / requires less energy to remove the valence electron
