Periodic table
What does the atomic number of an element tell you?
The atomic number of an element tells you the number of protons in the nucleus — and that number is what defines the element.
Isotopes have the same number of protons but different numbers of what?
Neutrons
How many electrons can the first shell hold?
2
Ions form when atoms gain or lose these.
Electrons
An element is made of only one type of these.
Atoms
Why are noble gases generally unreactive?
because their outer electron shell is already full, which makes them chemically stable and not interested in gaining, losing, or sharing electrons.
Isotopes are still the same element because they always have the same number of these.
Protons
What are electrons found in.
Hint: They go around the nucleus
Shells
A positively charged ion is called what.
Cation
Oxygen, gold, and carbon are all examples of this type of substance.
Elements
Wha elements has the symbol K
potassium
The isotope “Carbon‑13” has 6 protons. How many neutrons does it have?
7
The nucleus contains protons and what else
Neutrons
A negatively charged ion is called what
Anion
CO₂ and H₂O are examples of this type of substance.
Compounds
The period number tells you how many electron shells an atom has.
Number of shells
An isotope that does not decay over time is called this.
A stable isotope
A neutral atom has equal numbers of protons and what
Electrons
An ion is an atom that has gained or lost what?
Electrons
How many elements are in NaCl?
2
These elements in Group 18 are very unreactive because they have full outer shells.
Nobel gasses
The mass number tells you the total number of protons and what else?
Neutrons
This number tells you how many protons an atom has.
Atomic number
If an atom loses electrons, it becomes this type of ion.
Caution (positive ion)
A compound forms when atoms are joined together by these.
Chemical bonds