chemistry

• A combination reaction involves two or more reactants coming together to form one product.
• A solution that has a pH greater than 7 is considered a basic (alkaline) solution.
• A solution that has a pH less than 7 is considered an acidic solution.
• The periodic table consists of metals, nonmetals, and metalloids.
• Elements are arranged in order of increasing atomic number in the periodic table.
• The pH scale is logarithmic, with each whole number representing a tenfold change in acidity or alkalinity.
• In a gas, molecules move freely and randomly, filling their container.
• In a chemical reaction, atoms are rearranged to form new substances with different properties.
• An endothermic reaction absorbs energy from its surroundings.
• In an exothermic reaction, energy is released as heat.
• The pH scale ranges from 0-14, with values below 7 indicating acidic solutions and values above 7 indicating alkaline/basic solutions.
• An example of an acidic solution is lemon juice, which has a pH around 2.
• Acids are substances that release hydrogen ions when dissolved in water.
• Metalloids are elements with properties between those of metals and nonmetals.
• Nonmetals do not conduct electricity well because they lack free electrons.
• Nonmetals have low melting points and boiling points compared to metals.
• Metalloids have properties between those of metals and non-metals.
• Nonmetals do not conduct electricity well and are poor conductors of heat.
• Metals are good conductors of both electricity and heat.
• Acids release hydrogen ions when dissolved in water, while bases accept hydrogen ions from other substances.