Atoms and the Periodic Table Flashcards
(21 cards)
What is an atom?
The smallest unit of an element that retains its chemical properties.
Keyword: Atom – the basic building block of matter.
What are the three main subatomic particles in an atom?
Protons, neutrons, and electrons.
Keywords:
• Proton – positive charge, in nucleus
• Neutron – no charge, in nucleus
• Electron – negative charge, orbits nucleus
Where is most of the mass of an atom located?
In the nucleus
What does the atomic number represent?
The number of protons in an atom.
Example: Carbon has 6 protons, so its atomic number is 6.
What does the mass number represent?
The total number of protons and neutrons.
Formula: Mass number = protons + neutrons
What are isotopes?
A: Atoms of the same element with the same number of protons but different numbers of neutrons.
Example: Carbon-12 and Carbon-14
How are elements arranged in the modern periodic table?
In order of increasing atomic number.
What are groups in the periodic table?
Vertical columns. Elements in the same group have similar chemical properties.
What are periods in the periodic table?
Horizontal rows. Elements in the same period have the same number of electron shells.
What is a chemical symbol?
A one- or two-letter abbreviation for an element.
Example: Na = sodium
What are the most reactive metals?
Group 1 alkali metals.
What are the most reactive non-metals?
Group 7 halogens.
What element is found in Group 0 and is very unreactive?
Helium, a noble gas.
What charge does an electron have?
Negative (-1)
What happens to reactivity as you move down Group 1?
It increases
What happens to reactivity as you move down Group 7?
It decreases
What is the overall charge of an atom?
Neutral (equal numbers of protons and electrons).
What is the electron shell configuration for sodium (atomic number 11)?
2, 8, 1
What is the definition of an element?
A substance made of only one type of atom
How many elements are there in the periodic table?
118
What are transition metals?
Elements found in the central block (Groups 3–12) of the periodic table, with typical metallic properties.
