Chemistry: Chapter 4 and 5 [DONE] Flashcards
What did Democritus reason about atoms?
he said that they were indivisible and indestructible; he turned Dalton’s ideas into a scientific theory by using scientific methods
What do scientists use to observe atoms?
Scanning electron microscopes
define atom (2)
- the SMALLEST particle of an element
- it retains its identity in a chemical reaction
define Dalton’s Atomic Theory: (4)
- All elements are composed of atoms
- atoms of the same element are identical, but atoms from different elements are ALL different
- atoms of different elements can mix together to form a compound
- chemical reactions occur when atoms are separated from each other, joined, or rearranged in a different combination. *Atoms of one element can NEVER be changed into another element from a chemical reaction.
What are the three types of subatomic particles?
What are their charges?
What are their masses?
- protons, neutrons, and electrons
- positive, neutral, and negative
- 1, 1, 1/1840
What is the actual structure of a nuclear atom?
- Protons and neutrons are contained inside of the nucleus.
- Electrons reside in orbitals AROUND the nucleus
define electron?
who discovered electrons?
- a negatively charged subatomic particle
- J.J. Thomson
define cathode ray:
what was the final results in the experiment conducted by J.J. Thomson
- a glowing beam that Thomson used in an experiment
- found that a positively charged plate ATTRACTS the cathode ray and a negatively charged plate REPELS the cathode ray.
Define proton:
who discovered protons?
- a positively charged subatomic particle
- Ernest Rutherford
define neutron:
who discovered neutrons?
- a neutrally charged subatomic particle
- James Chadwick
define nucleus:
- the center / core of an atom
What was later discovered about atoms?
- that they actually ARE divisible, which means that they can be divided without losing their properties.
what makes one element different from another?
the number of protons
*every element has a different number
How do isotopes of an element differ?
because isotopes of an element have a different number of neutrons and different mass numbers
How to calculate the atomic mass of an element?
(mass of isotope x natural abundance in decimal form = x ) + (mass of isotope x natural abundance in decimal form = x), etc…
- do that for however many isotopes it gives you and then add the products
define atomic number
the number of protons in the nucleus of an atom of the element
define mass number
total number of protons and neutrons in an atom
What did Niels Bohr propose in his model of the atom?
He proposed that an electron is found only in orbits around the nucleus.
what does the quantum mechanical model determine about the electrons in an atom?
the allowed energies an electron can have and how likely It is to find the electron in various locations?