Topic 2 Flashcards
(23 cards)
What is an Element?
- The name of an atom based on the number of protons in their nucleus.
What is an atom?
- The building blocks of matter and they cannot be broken down into simpler substances.
What is a molecule?
- Groups of atoms bonded together, they may be atoms of the same or different elements.
What is a compound?
- A type of molecule in which two or more different elements are bonded together.
What are the two main types of matter?
- Mixture
- Can be separated by physical means
and does not have a specific formula
- Heterogeneous
- Homogeneous - Pure Substance
- Has a specific formula
- Element
- Compound
What is a Heterogeneous mixture?
- Different components are visible
- Composition is different throughout the mixture
What is a Homogeneous mixture?
- Different components are not visible
- Composition is constant throughout the mixture
What is Thompson “Plum Pudding” model?
- Thompson thought that since atoms do not have a charge, they must consist of a positively charged mass embedded with negatively charged particles, which he called electrons
- The positive and negative component balanced each other out
What is Rutherford’s “Planetary” Model
- Rutherford suggested that almost all of an atoms mass was located in its center, which he named the nucleus
- The nucleus was composed of positively charged particles called protons
- The rest of the atom was empty space, with small electrons which rotated around the nucleus at random
- He found that protons are in the nucleus and electrons occupy the space around by the “Gold Foil Experiment”
What is Bohr’s atomic model?
- Bohr also pictured the atom like a miniature solar system, but he thought that electrons rotated around the nucleus in fixed pathways called electron shells
- He found out that the nucleus has both protons and neutrons
What is the Electron cloud model?
- Scientists like Schrodinger, and Louis de Broglie figured out that electrons move in waves rather than particles.
- Helps us to predict where electrons are most likely to be found
What is the Atomic Theory Acronym?
D -Dalton
A - Atom
J -JJ Thomson
E -Electrons
R -Rutherford
N -Nucleus
What is Daltons atomic theory?
- All matter is made up of small particles called atoms
- Atoms cannot be created, destroyed or divided into smaller particles
- All atoms of the same element are identical in mass and size
- Compounds are formed when atoms of different elements combine
What are the characteristics of the atom?
- Each atom has a nucleus that carries most of the atoms mass
- Positively charged particles called protons and particles with no charge called neutrons are found in the nucleus
- Small, negatively charged particles called electrons surround the atom in fixed orbitals
What is the Gold Foil Experiment
- It was how Rutherford figured out
- A piece of gold foil was hit with positively charged particles. Most of the particles went through, this showed that the golds atoms were mostly empty space. Some particles changed paths and some bounced back. The only way this would happen was if the atoms in the gold foil had a heavy region of positive charge.
Main points of this experiment - Most particles travel through the foil undeflected>The atom is mostly empty space
- Some particles are deflected by small angles>The nucleus is positively charged
- Some particles travel back from the foil>The nucleus carries most of the atoms mass
What are the characteristics of the Atomic symbol?
Atomic symbol
- Represents the elements name
- The letter in the center
Atomic number
- Represents the number of protons in the nucleus
- The little number in the top left corner
Atomic mass
- Represents the weighted average of the masses of each naturally occurring isotope of that element
- The number under the atomic symbol
What are the characteristics of a Bohr diagram?
- The innermost shell can hold only two electrons
- Each outer shell can hold a maximum of eight electrons
- The outermost shell of electrons is referred to as the valence shell
- Elements with the same number of electrons in their valence shells display similar chemical behaviors
What is a valence shell?
- The outer most shell of electrons
What is an isotope?
- Elements that have the same # of protons, but a different # of neutrons.
- Isotopes share almost the same chemical properties but differ in mass because they have gained or lost neutrons.
- When identifying isotopes we call it Nuclear Notation.
What is Nuclear Notation, and what is its characteristics?
- Nuclear Notation is for identifying isotopes
Element Symbol - The big letter
Mass number - The top number
Atomic Number - The bottom number
How do you name an isotope?
Name the element, write a dash and put the Atomic mass after
What is Molar mass?
The atomic mass of an element that is listed on the periodic table.
What are ions, and what are the two types?
- Ions are atoms that have lost or gained electrons, resulting in either a positive or negative charge
Anions - Negatively charged, resulting from a gain of electrons
Cations - Positively charged, resulting from a loss of electrons
