A2.1 - the periodic table and atomic structure Flashcards
1
Q
What are elements?
A
- Elements are substances that cannot be broken down into other substances
- There are about 90 naturally occurring elements and another 25 synthetic elements
- All elements can be divided into three categories, Metals, Non-metals, and metalloids
2
Q
What are metals?
A
- Most elements are in this category
- Most are silver or gray and shiny
- They are all good conductors of heat
- They are also malleable and ductile
- Most metals are solid at room temperature
- Metals react strongly with other substances
- Some metals are inert, and don’t react (Eg. Gold)
3
Q
What are non-metals?
A
- Only 17 elements are non-metals
- They are grouped together because of their lack of common ground with other elements, and not their similarities with each other (They are the junk drawer of the periodic table)
- Half of the non-metals exist as groups of atoms, while the other exist only as individual atoms
4
Q
What are metalloids?
A
- Metalloids have properties intermediate between metals and non-metals (eg. some metalloids conducts electricity, but not well)
5
Q
What are periods and families/groups?
A
- Periods are the horizontal rows
- Families/groups are the verticle columns
6
Q
What are the alkali metals?
A
- Group 1
- Lithium, sodium, potassium are in this group
- All are soft, shiny, silver, and soluble in water
- Soft, silver, shiny
7
Q
What are the Alkaline earth metals?
A
- Group 2
- Magnesium, calcium
- Shiny and silver like the Alkali metals, but not as soft
- White compounds, but not as soluble as the alkali metals
8
Q
What are the noble gases?
A
- Group 18
- Very unreactive
9
Q
What are the Halogens?
A
- Group 17
- Fluorine, bromine, iodine, chlorine
- These elements are poisonous and react with alkali metals to form salts
- Salts are compounds produced in neutralization reactions between acids and bases
10
Q
What are protons?
A
- Positively charged
- Gathered with the neutrons in the nucleus
- Protons and neutrons account for more than 99.9% of the mass of the atom
11
Q
What are neutrons?
A
- Neutrally charged (Have no electrical charge)
- Gathered with the protons in the nucleus
- Protons and neutrons account for more than 99.9% of the mass of the atom
11
Q
What are electrons?
A
- Very low mass
- Negatively charged
11
Q
What is an energy level/shell?
A
- An energy level is a region of space near the nucleus that may be empty or occupied by electrons
- Electrons in energy levels nearest the nucleus have the lowest energy, and electrons in energy levels farthest from the nucleus have more energy
11
Q
How many electrons can exist in the energy shells?
A
From the shell closest to the nucleus: 2,8,8,18,
12
Q
What is the atomic number?
A
It indicates how many protons an element has
