4. Hennig Brand
First person to discover an element. In 1649, his
experiments with distilled human urine resulted in
the production of a glowing white substance,
which he named phosphorus.
5.
6.
7.
8. J u l i u s L o t h a r M e y e r
German chemist. He was one of the pioneers in developing the
first periodic table of chemical elements. His book, Die modernen
Theorien der Chemie, published in Breslau in 1862, contained an early
version of the periodic table containing 28 elements, classified
elements into six families by their valence.
10. DMITRI MENDELEEV
Russian Chemist and the first Scientist to make a periodic
table similar to the one that is used today. He arranged the
elements by atomic mass. On 1869, a formal presentation
was made to the Russian Chemical Society, entitled “The
Dependence Between the Properties of the Atomic Weights
of the Elements”.
SCIENTIFIC BENEFITS OF MENDELEEV’S TABLE:
1. It enabled Mendeleev to predict the discovery of new
elements and left spaces for them. Ex. Silicon(Si)
2. It provided for variance from atomic weight order.
13. In 1914, an English Physicist’s observation on
X-ray frequencies led to the development
of modern Periodic law which states that
the observation of elements vary
periodically with atomic number.
HENRY MOSELEY
17. What is the ATOMIC
NUMBER?
o The number of
protons found in
the nucleus of an
atom
Or
o The number of
electrons
surrounding the
nucleus of an
atom.
18. What is the SYMBOL?
OAn
abbreviation
of the
element
name.
19. What is the ATOMIC
WEIGHT?
O The number of
protons and
neutrons in the
nucleus of an
atom.
20. How do I find the number of protons,
electrons, and neutrons in an element using
the periodic table?
o # of PROTONS = ATOMIC NUMBER
o # of ELECTRONS = ATOMIC NUMBER
o # of NEUTRONS = ATOMIC NUMBER-
ATOMIC
WEIGHT
21. What is an ELEMENT?
A substance
composed
of a single
kind of
atom.
