How the Elements Were Organized
In the ______________s, a successful method to group elements together was created by a _________________ chemist named ___________________.
1860s
Russian
Dmitri Mendeleev
The rows of the modern table are called?
The columns of the modern table are called?
Rows = Periods
Columns = Groups
What are the three classes of elements?
Metals, Nonmetals, Metalloids
How many groups of elements are there?
18
Why did Mendeleev make the periodic table?
He was both a teacher and a chemist and when he was writing a chemistry textbook, he needed a way to organize the elements so it would be easier for students to learn.
How many groups are there?
What do the elements in the same group have in common?
18 groups
Elements in the same group have similar properties and the same number of valence electrons.
Give 2 properties of metals, nonmetals, and metalloids.
Metals: good conductors of heat/electricity, high melting points, solid at room temperature, shiny, ductile, malleable
Nonmetals: low boiling points, gases at room temperature, poor conductors of heat, dull, brittle
Metalloids: can conduct electricity at certain temperatures, may be shiny but brittle, solids at room temperature
Groups 3 - 12 are what kind of metals?
Transition metals
Mendeleev mad a set of cards of the elements with one element per card. What did he write on the cards (give me 2 things)?
Element’s name, atomic mass, and known properties.
From left to right across each period, each element has one more ____________________ than the element before.
Proton
Describe the outer energy levels of metals, metalloids, and nonmetals.
Metals: Almost empty (they want to give up electrons so they can have a full outer energy level)
Metalloids: Half full (kind of meh about giving or getting electrons)
Nonmetals: Almost full or completely full (they want to gain electrons so they can have a full outer energy level)
What are the names of groups 13 -16
Group 13: Boron Group
Group 14: Carbon Group
Group 15: Nitrogen Group
Group 16: Oxygen Group
What order did Mendeleev put the element cards in that he made in?
He found the pattern when he placed the elements in order by atomic mass.
In the modern periodic table, how are elements organized?
Elements are organized by atomic number.
From left to right across the periodic table, each element has one more proton than the element to its left. Since atoms are neutral, for each added proton, one electron is also added. Where are the electrons added to?
Electrons are added first to the lowest energy level possible until that level is full.
Similar: Both are very reactive - especially with each other (alkali have only one valence electron they want to get rid of and halogens need one valence electron)
Different: Alkali metals are in Group 1 and metals (except for hydrogen), halogens are in Group 17 and nonmetals.
How could Mendeleev predict missing elements?
Mendeleev left spaces on his table for elements that had not yet been discovered. Based on their position in the table, he could even predict the properties of the missing elements.
What does the atomic number of an atom tell us?
Atomic number is the number of protons in an atom of an element.
What is a valence electron and what do they determine?
Electrons in the outer energy level of an atom. The number of valence electrons determines an element’s reactivity and how elements can conduct electric current.
What does Group 18 contain? Describe the elements they contain.
Noble Gases - colorless, odorless gases that have a full outer energy level (this full outer energy level makes them the least reactive element), in nature they seldom combine with other substances.