Atoms and Periodic Table Unit Vocab Flashcards
Vocabulary Chapter 17
What is an atom?
The smallest unit of an element that retains the properties of that element.
What is a nucleus?
A membrane-bound organelle found in eukaryotic cells that contains the cell’s genetic material (DNA) and regulates cell activities like protein synthesis and cell division.
What are protons?
Positively charged, subatomic particles found in the nucleus of every atom.
What are neutrons?
A subatomic particle found in the nucleus of an atom, having no electric charge and a mass slightly greater than that of a proton.
What are electrons?
A negatively charged, fundamental subatomic particle found outside the nucleus of an atom, orbiting in various energy levels.
What are quarks?
One of the most basic forms of matter that make up the heavier elementary particles.
Who proposed that all things are composed of atoms?
Democritus.
Who introduced the atomic theory into chemistry?
John Dalton.
What did Joseph Thomson theorize?
He theorized and offered experimental evidence that the atom was a divisible entity rather than the basic unit of matter.
What are Ernest Rutherford’s contributions?
His discoveries in radioactivity and atomic structure.
Who is Niels Bohr?
A Danish theoretical physicist who made foundational contributions to understanding atomic structure and quantum theory.
What is the electron cloud?
The region around the nucleus of an atom where electrons are most likely to be found.
What defines the atomic number?
The protons in the nucleus of an atom, defining the element.
What is mass number?
The total number of protons and neutrons in its nucleus.
What are isotopes?
A variation of an element that has the same number of protons but a different number of neutrons.
What is average atomic mass?
The weighted average mass of all naturally occurring isotopes of that element, taking into account their relative abundances.
What is the periodic table?
Elements with similar properties are grouped in columns (groups) and rows (periods).
Who formulated the Periodic Law?
Dmitri Mendeleev.
What did Henry Moseley contribute to?
Likely focuses on his work with X-ray spectroscopy and the concept of atomic number.
What are groups in the periodic table?
Vertical columns of elements on the periodic table, sharing similar chemical properties due to having the same number of valence electrons.
What is an electron dot diagram?
Using dots around the element’s symbol to show the number of electrons in the outermost shell.
What is periodic motion?
A movement that repeats in equal time intervals.
