Atomic Theory Flashcards
What are physical properties called?
Macroscopic properties
What is matter?
Matter is anything made up of atoms and molecules. Matter is anything that has mass.
Matter is everything we….
- touch
- hear
- smell
- see
- can’t see
- feel
What are chemical properties called?
Microscopic properties
What are the characteristics of macroscopic properties?
- Physical or Macroscopic properties are observable properties.
- We use our senses to detect them.
What are the characteristics of microscopic properties?
- Chemical or Microscopic properties are often unobservable properties but can be studied by carrying out experiments.
- These properties involve the arrangement of atoms & molecules and the way they are bonded together.
What is the kinetic theory of matter (the particle theory)?
- Matter is made up of tiny, invisible moving particles
- Particles of different substances have different sizes
- Lighter particles move faster than heavier particles
- As the temperature rises, the particles move faster
- In a solid, the particles are very close together and vibrate in fixed positions
- In a liquid, the particles are a little further apart. They have more energy and they can move around each other
- In a gas, the particles are very far apart. They move rapidly and randomly in all the space that surrounds them.
- The particles might be atoms, molecules or ions.
What are the properties of a solid?
– have a definite shape and volume
- are held tightly and packed fairly close together they are strongly attracted to each other
- are in fixed positions but they do vibrate
What are the properties of a liquid?
– have a definite volume but an indefinite shape
- are fairly close together with some attraction between them
- are able to move around in all directions but movement is limited by attractions between particles
What are the properties of a gas?
– have an indefinite shape and volume
- have little attraction between them and are widely spaced out
- are free to move in all directions and collide with each other and with the walls of a container
What are some solids called eg rubber? And why?
Some solids (eg. rubber) are called AMORPHOUS because they do not have a regular structure.
What is meant by melting point and what does it indicate about a substance?
The temperature at which a solid melts
The melting point of a solid indicates how strongly particles are held together.
Substances with high melting points have strong forces between their particles
What is meant by freezing point?
The temperature at which a liquid solidifies
What is meant by boiling point?
The temperature at which evaporation begins to occur within the bulk of the liquid
What is meant by condensation point?
The temperature when the vapour cools back into a liquid
What are volatile liquids? What is different about their particles?
Volatile liquids are those which evaporate at low temperatures (eg Petrol)
These have weak forces between their particles than substances with higher boiling points
How can matter be changed from state to state?
By varying the temperature and sometimes the pressure.
What are crystalline solids?
They are solids which have a fixed shape.
What is the change that occurs from a solid to a liquid?
Melting
What is the change that occurs from a liquid to a gas?
Evaporation
What is the change that occurs from a liquid to a solid?
Freezing/solidification
What is the change that occurs from a gas to a liquid?
Condensation
What is the change that occurs from a solid to a gas?
Sublimation
What is the change that occurs from a gas to a solid?
Sublimation
What do atoms of an element have in common?
All contain the same number of protons.
Are neutral, as the number of protons is equal to the number of electrons.
What were the goals of alchemy?
- The transmutation of metals
- The creation of an elixir that would prolong life indefinitely
- The transmutation of human life
- To search for the Philosopher’s Stone (manipulate time)
What is the scientific method?
Backing up theories with experimental evidence.
1. Observe something happening
2. Develop a hypothesis about why it happens
3. Design experiments to test the hypothesis
4. Predict what will happen in the experiments
5. Perform the experiments and observe what actually happens
6. Modify the hypothesis if predictions were wrong
Repeat from step 3.
What is the order of the scientists who discovered parts of the atomic theory?
Democritus Aristotle John Dalton J.J. Thomson Ernest Rutherford Niels Bohr James Chadwick
What did Democritus propose?
All matter is made up of tiny indivisible particles called atoms.
What did Aristotle propose?
All matter water made up of four elements; earth, fire, water and air.
What did John Dalton propose? How did he come about with this theory and why was it different to scientists’ discoveries before his time?
All matter was made up of atoms.
Atoms of the same element are identical and have the same mass.
Atoms of different elements have different masses.
Atoms could not be created or destroyed.
Atoms cannot be changed into other atoms.
Atoms combine together in simple ratios to form molecules.
He proposed this based on experimentation and observations, not on pure reason as other scientists’ before his time did.
What did J.J. Thomson propose?
That atoms consisted of a positively charge sphere with electrons embedded into it. The Plum Pudding Model.
What did J.J. Thomson discover and how?
He discover a negatively charged particle that is 2000 times smaller than a hydrogen atom.
Atoms are divisible: subatomic particles.
He discovered this by his experimentation with his Cathode Ray: that the electrons that made up the cathode rays could be deflected by magnets or electrically charged plates.
What did Ernest Rutherford propose?
That atoms were mainly empty space.
Each atom consisted of positive particles, which he called protons.
Protons are found in the core of the atom, which he called the nucleus.
Electrons move around the nucleus in random orbits.
What did Ernest Rutherford discover and how?
He discovered the protons, the nucleus, electrons have random orbits and that an atom is mostly empty space.
He discovered this by conducting the Gold Foil Experiment.
He shit alpha particles at a thin sheet of gold foil and found that some of the beams passed straight through and other deflected.
This bought him to the conclusion that if the negative beams were being deflected only sometimes, there must be a place concentrated to a positive charge that was deflecting the beam.
What did Niels Bohr propose?
The shell model.
That electrons have fixed orbits/ energy levels/ quantum levels, which he called shells.
Electrons closer to the nucleus are of lower energy than those further out.
He also proposed the theory of quantum energy and measured the wavelengths of the different energy levels by using a mathematical formula.
What is a quantum of energy or photon?
It is an emission of light that is the result of an electron gaining enough energy to move to a higher energy level and, when falling back to its ground state position, emitting the photon.
What did James Chadwick propose?
He discovered the neutron in an atom.
The third subatomic particle.
Same mass as a proton but no charge.
K,L,M,N shells
What did James Chadwick discover and how?
The neutron.
He bombarded a sample of beryllium with alpha particles and found a ray was given off.
The particles that made up the ray were not deflected by a magnetic or electrical field: which indicated that they carried no charge.