8th Chemistry Final Flashcards
What is a Proton?
A proton has a positive charge and is located in the nucleus
What is a Neutron?
A Neutron has a neutral charge and is located in the nucleus.
What is an electron?
An electron has a negative charge and is located in the electron cloud.
How is the periodic table organized?
By groups, atomic number, periods. Metals, transition metals, and nonmetals.
What elements make an ionic bond? What charge?
Metals and nonmetals. One cation and one anion.
What holds together bonds?
An attractive force.
What elements make a covalent bond? What charge?
Nonmetals and nonmetals. A neutral charge.
What happens when an element loses all of its valence electrons?
It becomes a cation.
What are some examples of chemical changes?
Combustion, digestion, rusting, precipitate.
What happens during a chemical reaction?
Bonds between atoms break and form to create new substances.
What are some indications that a chemical change has taken place?
Temperature change, precipitate, change in color, and bubbles forming.
What are some examples of physical changes?
Cutting vegetables, boiling water, and dissolving.
What is a physical property?
A characteristic of a substance that is observed without changing the chemical makeup of the substance.
What are some examples of physical properties?
Density, conductivity, melting point, and temperature.
What are three physical properties of water?
Solid (ice), liquid (water), gas (vapor).
What are some indications that a physical change has taken place?
Change in size, shape, form, or phase. The substance is the same as before.
What does the law of conservation of mass state? Why is it important in chemical reactions?
Mass in chemical reactions is neither created nor destroyed. It is important to understand when balancing chemical equations.
What does the law of conservation of energy state? Why is it important to understand in chemical reactions?
Energy in a chemical reaction is neither created nor destroyed. It explains how energy changes forms and is transferred into new substances.
What are the two components in chemical reactions?
Reactants and products.
What are some examples of chemical properties?
Flammability, Reactivity, heat of combustion, toxitity, acidity.
What is the difference between a coefficient and a subscript?
Coefficients tell how many molecules there are. Subscripts tell how many of each atoms there are.
Why is dissolving a physical change?
It changes the physical feature of the substance, not the chemical make up of the substance. It can be reversed.
What happens to the reactants and products when a heat pack is broken and releases heat?
It conducts an exothermic process and releases more energy when the bonds of the products are formed than when the reactants bonds are broken.
What are endothermic and exothermic reactions? What happens to the energy in each case?
Exothermic reactions release energy. More energy in reactants than products. Endothermic reactions absorb energy. More energy in products than reactants.
