Atoms and Atomic Structure Flashcards
What is an atom?
Atom is the basic and structural unit of an element that retains the chemical properties of the element.
What determines the identity of the element and how it will react in chemical and biological processes?
The number and arrangement of subatomic particles.
What are the subatomic particles?
Protons, neutrons and electrons.
What are the two distinct regions of an atom?
Nucleus and Electron cloud.
What is a nucleus?
1, Central core of an atom
2. Small and dense and contains majority of the mass of an atom
3. Contains protons and neutrons.
What is an electron cloud?
- Diffused region of negative charge around the nucleus.
- An electron can be found anywhere in the electron cloud.
What are electrons?
- Negatively charged particles.
- Tiny and have negligible mass.
- Have rapid motion.
First experimentally based theory on atomic structure was given by ___________.
John Dalton
What are the postulates of Dalton’s theory?
- All matter is made up of atoms.
- Atoms cannot be created, destroyed, divided or converted to another kind of atom.
- Atoms of the same elements have similar properties.
- Atoms of different elements have dissimilar properties.
- Atoms of different can combine in simple whole number ratios to form compounds.
- Chemical reaction involves joining, separating or rearranging atoms.
What are isotopes?
Atoms of the same element with different mass (due to difference in the number of neutrons)
What is radioactive decay?
Some atoms split into smaller atoms, releasing energy in the form of radiation. Such atoms have an unstable nucleus, and are called radioactive.
What are radioisotopes?
They are isotopes that release energy and particles. Have identical chemical behavior but unique nuclear behavior.
What are applications of radioactive decay?
- Diagnosis of blood clots
- Monitoring thyroids by administering radioactive iodine.
- Substituting radioisotopes in biochemical processes to track them by the particles and energy that they emit.
What is atomic number?
The no. of protons and electrons in the atom.
What is atomic mass no.?
No. of protons + No. of neutrons
What are energy levels in Bohr’s theory?
Energy levels are discrete orbits in which an electron can revolve around the nucleus. They have a specific value of energy- Quantization of Energy.
What is ground state and excited state?
Ground state- When the electrons in the atoms are in their lowest possible energy levels.
Excited state- When the electron absorbs energy to move to a higher energy level.
What is relaxation?
When in excited state, electrons spontaneously release energy in the form of a photon with wavelength and energy required to return back to ground state.
How did Bohr calculate the energy of electrons in different energy levels?
By the wavelengths of photons emitted during relaxation.
True or False: Highest energy level is the most reactive.
True.
What is the importance of knowing the atomic diagram and electron structure?
To describe the arrangement of interaction between atoms of different elements.
What does Schrodinger’s theory propose?
Each energy level has sub levels and sub levels have atomic orbitals.
What is the maximum capacity of electrons in a shell?
2(n)^2
What does the principal quantum number denote?
- Size
- Energy
