Unit 3: How do we use matter? Flashcards
What are the three parts of an atom?
Proton, neutron electron
Define an electron
An electron is a subatomic particle with a negative charge, located in shells outside the nucleus.
Define an ion
An ion is an atom or group of atoms with an unbalanced number of charges due to gaining or losing an electron.
Define a cation
A cation is a positively charged ion due to an atom losing an electron.
Define an anion
An anion is a negatively charged ion due to an atom gaining an electron.
What is atomic mass?
Atomic mass refers to the mass of an atom, found by adding the number of protons and neutrons
What is atomic number?
Atomic number refers to the number of protons an element of an element has. No two atoms of an element have the same atomic number.
What are the three categories of the periodic table?
Metals, non-metals, and metalloids
What are the physical properties of metals?
- Shiny
- High melting point
- Good conductors of heat and electricity
- High density
- Malleable
- Ductile
- Sonorous (ring when struck)
- Tend to lose electrons to form cations
What are the chemical properties of metals?
Metals form oxides which are acidic. Metals are more likely to corrode and more likely to react with acids or water.
What are the physical properties of non-metals?
- Dull
- Low melting point
- Low density
- Brittle
- Non-ductile
- Poor conductors of heat and electricity
- Tend to gain electrons to form anions
What are the chemical properties of non-metals?
Non-metals form oxides that are acidic.
What are group 1 elements called?
Alkali metals
Which group in the periodic table is the most reactive?
Alkali metals are the most reactive group
How many valence electrons do alkali metals have?
1 valence electron
Why are alkali metals stored under oil?
Alkali metals react very quickly with water and air and storing them underwater prevents this reaction.
Why does reactivity increase down group 1?
As you go down group 1 elements, the atom gets bigger. The bigger the atom the further away the valence electrons are. As a result, the attraction between the nucleus and the valence electrons is weaker, making the atom lose electrons more easily.
How does metal react with water?
Metal reacts with water to form metal hydroxide and hydrogen.
What are the properties of alkali metals?
- Highly reactive
- Low density
- Soft
- Low melting point
How do alkali metals react with oxygen?
Alkali metals react with oxygen to form oxides which have a fuller appearance and lower reactivity than the pure metal.
How do alkali metals react with water?
Alkali metals react vigorously with water. Oxides and metal hydroxides are produced, and hydrogen gas is released.
What are the trends seen moving down group 1 of the periodic table?
Increasing atomic radius, increasing reactivity, decreasing electronegativity and decreasing melting and boiling point.
Where are alkaline earth metals found in the periodic table?
Group 2 of the periodic table
What are the properties of alkaline earth metals?
- Alkaline earth metals are found in group 2 of the periodic table
- They have 2 electrons in their outermost shell – 2 valence electrons
- Reactivity and density increase down the group
- Melting and boiling point decreases down the group
- Somewhat reactive at standard temperature and pressure
- Lose 2 electrons when they react to form a cation (positive ion) with 2+ charge
- Metals become softer down the group
- They are found in the s-block
What block are alkali metals found in?
s-block
What block are alkaline earth metals found in?
s-block
How many valence electrons do alkaline earth metals have?
2 valence electrons
What two properties increase as you go down the alkaline earth metals group?
Reactivity and density
What two properties decrease as you go down the alkaline earth metals group?
Melting and boiling point
What group are transition metals found in?
Group 3 to 12
What block are transition metals found in?
d-block
What group of elements can be used as a catalyst?
Transition metals
Which group are halogens found in?
Group 17
How many valence electrons do halogens have?
Seven valence electrons
What properties increase down the halogens group?
Atomic radium, melting and boiling point
What properties decrease down the halogen group?
Electronegativity and reactivity
Define inert
Chemically unreactive
What group are noble gases in?
Group 18 of the periodic table
Why are noble gases inert?
They have a full outer shell
What are the properties of non-metals?
Dull, low melting point, low density, brittle, non-ductile, poor conductors of heat and electricity and tend to gain electrons to form anions.
What are the properties of metalloids?
They have properties of both metals and non-metals, they are solids that can be shiny or dull, they are better conductors of heat and electricity than non-metals, but not as good as metals and they are ductile and malleable.
Calculate the relative formula mass of carbon sulfate CaSO4 (Ca: 40 | S = 32 | O = 16)
(40 x 1) + (32 x 1) + (16 x 4)
= 40 + 32 + 64
= 136
Describe the pattern of first ionization energy within a group?
As you go down a group, atomic number increases, and the outermost electron shell is at an increasingly higher energy level. Each successive energy level is further away from the nucleus so atomic radius also increases, and the level of shielding between the valence electrons and the nucleus increases down a group. As a result of increasing level of shielding, the strength of the bonds holding the valence electrons to the nucleus decreases. The decrease in the first ionization energy results in an increase in reactivity. The weaker the hold of the positively charged nucleus on the negative electrons, the easier for the atoms to lose its electrons and the more reactive it is.
What is effective nuclear charge?
The positivity of the nucleus
Describe the pattern of the first ionization energy across each period?
As you move across each period, the level of shielding remains constant. The number of valence electrons increases by one for each element and is placed in an orbital with a similar energy level. However, the effective nuclear charge increases for each element because of the increase in the number of protons. With an increasing effective nuclear charge and a constant energy level, the hold between the valence electrons and the nucleus increases across a period, and the first ionization energy decreases. As a result, it is harder for atoms to lose electrons and reactivity decreases. The only two exceptions are aluminum and sulfur.
Outline the trends in group 17 of the periodic table
- State of matter changes as you go down the group
- Shielding increases
- Number of full inner electron shells increases
- Reactivity decreases down the group
- Effective nuclear charge decreases
