Particles And Atoms Flashcards
What is matter? What are particles? What is an atom? What are molecules? What are elements?
Matter is what makes up everything A particle is a tiny bit of matter that can be large enough to see or impossible to even see with a microscope. Atoms are the smallest particle of an element that still has chemical properties. Molecules are made up of atoms bonded. Elements are pure substances made of atoms with the same number of protons.
What are chemical and physical changes?
A physical change is when a substance changes state or shape, or breaks into pieces. No new substances are made and the change can be reversed.
A chemical change is one that produces new substances that can have different properties. They are rarely reversed.
What happens to particles in physical and chemical changes?
In physical changes, particles stay the same but their arrangement and movement change.
In chemical changes, particles break up and join together in different ways to make new substances.
What is the average size of an atom?
Atom’s have a diameter of 0.1nm
Atom’s nuclei have a radius of 10 * 10*-15
What are the limitations of the particle model?
- The relative size of atoms and distances between them are difficult to draw to scale.
- The forces between atoms are hard to represent and can be confusing.
What are isotopes? What are ions?
Isotopes are variants of an atom of an element with different number neutrons but same protons.
Ions are charged particles formed a loss or gain of electrons often in a chemical reaction
What did Dalton do? What did J.J. Thomson do?
Dalton suggested everything is made of atoms which were tiny solid balls. He discovered atoms of elements are identical and different elements have different atoms.
Thomson discovered the electron and created the plum-pudding model which were soft spheres of positivity with electrons dotted inside able to move in and out.
What did Rutherford do? What did Bohr do?
Rutherford beamed alpha particles at gold foil and observed most pass through, few be skewed, and barely any reflected. He concluded that the atom had a positively charged nucleus with most mass and electrons orbited this.
Bohr discovered electrons occupy fixed energy shells around nucleus.
