Category 1
Who developed the first periodic table of elements?
Dmitri Mendelev
On the first periodic table, from left to right across each row, elements are arranged by ___________.
atomic mass
The columns on the periodic table are known as _________.
Groups
The table of the elements is called a periodic table because of its ________________.
It 's repeating pattern
What are periods?
In the periodic table, the rows are known as periods.
It is known as "uncuttable" thing.
Atom
In the modern periodic table, elements are organized by____________.
increasing atomic number
The number of electron in an element is the same as the number of ___________.
Proton
How does Bohr's electron model likened to?
Planetary model/ Solar system model
Whose scientist said that atom is tiny, uncuttable solid particle?
Democritus
Name 3 classes of elements.
metals, metalloids, and nonmetals
What is proton?
A positively charged particle.
What is element?
pure substance consisting only of atoms that all have the same numbers of protons in their atomic nuclei
Elements that are good conductors of electricity.
Metals
Elements that do not conduct electricity.
Nonmetals
Elements that fall between metals and nonmetals in the periodic table.
Metalloids
What is electron?
It is a negatively charged particle.
What is valence electron?
The electrons in the outer energy level of an atom.
_____________ determines an element's reactivity and whether the element can conduct an electric current.
valence electrons
How many valence electron in group 1A?
In group 1 of the periodic table, all of the elements except ________ are ___________ metals.
hydrogen, alkali
Atomic number is also known as __________.
Proton number
Groups 13-16 contain _____ and ________ groups.
nonmetals and other metals
How does element symbol written?
Usually they written in capital letter and paired with small letter. Example He - the element symbol of helium.
Give three elements belonged to halogen group?
Fluorine, Chlorine, Iodine, Astatine, and Bromine